Category Archives: CLASS 10 – SCIENCE

Magnetic Effects Of Electric Current – Chapter 13 (NCERT Solutions & All Extra And Important Questions) – Science (Class 10)

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SUBJECT – SCIENCE
CLASS – X (10th)
QUESTION FROM – Magnetic Effects Of Electric Current – Chapter 13
ALL EXTRA & IMPORTANT / EXERCISE QUESTION ANSWER

Hi Friends, Welcome To – Study24Hours.Com, Here We Are Giving You Some Very Important Question & Answers From The Chapter Magnetic Effects Of Electric Current – Chapter 13. Magnetic Effects Of Electric Current Is The 13th Chapter Of Your Science NCERT Book Of Class X. So Check Out All Of Them & Please Revise All Of These Questions Before Your Exam. So Please Remember To Visit – www.Study24Hours.Com Daily For All Study Materials And More.

Intext Questions – Magnetic Effects Of Electric Current – Chapter 13 (NCERT Solutions & All Extra And Important Questions) – Science (Class 10)

Q1. Why does a compass needle get deflected when brought near a bar magnet?
Answer – The compass needle gets deflected due to the magnetic field around a bar magnet.

Q2. Draw magnetic field lines around a bar magnet.
Answer – magnetic field lines around a bar magnet

Q3. List the properties of magnetic field lines.
Answer – 

Q4. Why don’t two magnetic field lines intersect each other?
Answer – If two magnetic lines of force intersect each other it would mean that there are two directions of the magnetic field at the point of intersections, which is not possible.

Q5. Consider a circular loop of wire lying in the plane of the table. Let the current pass through the loop clockwise. Apply the right-hand rule to find out the direction of the magnetic field inside and outside the loop.
Answer – Applying the right-hand thumb rule, the magnetic field inside the loop is in vertically downward and outside the loop, it is in vertically upward directions.

Q6. The magnetic field in a given region is uniform. Draw a diagram to represent it.
Answer – In a uniform magnetic field, the magnetic field lines of force are parallel and equidistant from each other as shown in the diagram.

Q7. Choose the correct option.
The magnetic field inside a long straight solenoid-carrying current
(a) is zero.
(b) decreases as we move towards its end.
(c) increases as we move towards its end.
(d) is the same at all points.
Answer – (d) Magnetic field inside a solenoid is the same at all the points.

Q8. Which of the following property of a proton can change while it moves freely in a magnetic field? (There may be more than one correct answer.)
(a) mass (b) speed (c) velocity (d) momentum,
Answer – (d) Proton is a charged particle. When it moves in a magnetic field, a magnetic force is applied due to its velocity and hence the momentum changes.

Q9. In Activity 13.7, how do we think the displacement of rod AB will be affected if
(i) current in rod AB is increased; (ii) a stronger horse-shoe magnet is used, and (iii) length of the rod AB is increased?
Answer – In Activity 7, the force acting on a current carrying conductor when placed in a magnetic field is illustrated.
(i) When current in rod AB is increased, the displacement of the rod is increased, as a force acting
on the rod is directly proportional to the current flowing through it. On increasing the current, force on the conductor increases.
(i) If a stronger horse-shoe magnet is used, then the strength of the magnetic field will increase leading to greater force on the rod. Due to this, the displacement of rod will increase.
(ii) Displacement of the conductor is increased with an increase in length of the conductor. On increasing the length, more force will act on the conductor.

Q10. A positively-charged particle (alpha-particle) projected towards the west is deflected towards north by a magnetic field. The direction of magnetic field is (a) towards south (b) towards east (c) downward (d) upward.
Answer – The positively charged particle is moving towards West, i.e. the direction of current is towards West (current flows in the direction of the motion of positive charge). The particle is deflected towards North, so the direction of the force is towards North. Thus, from Fleming’s left-hand rule, the direction of the magnetic field is in an upward direction.




Q11. State Fleming’s left-hand rule.
Answer – 

Q12. What is the principle of an electric motor
Answer – 

Q13. What is the role of the split ring in an electric motor?
Answer – Split rings act as a commutator and its a function is to reverse the direction of current flowing through the coil.

Q14. Explain different ways to induce current in a coil.
Answer – Current is induced in a coil in the following ways:
(i) When a magnet is moved towards or away from the coil or there is a relative motion between coil and magnet, a current is induced in the coil circuit.
(ii) When a current passing through a coil a coil changes, then a current is induced in a coil placed near it.

Q15. State the principle of an electric generator.
Answer –

Q16. Name some sources of direct current.
Answer – Some sources of direct current are electrochemical dry cells, solar cells, lead-acid accumulator batteries, DC generators, etc.

Q17. Which sources produce an alternating current?
Answer – Some sources that produce alternating current are AC generators, thermal power stations, car alternators, etc.

Q18.  Choose the correct option. A rectangular coil of copper wires is rotated in a magnetic field. The direction of the induced current changes once in each,
(a) two revolutions (b) one revolution (c) half revolution (d) one-fourth revolution
Answer – After half revolution, the direction of motion of rectangular cool changes. Thus, the direction of induced current changes.

Q19. Name two safety measures commonly used in electric circuits and appliances.
Answer –  Electric fuse and earth wire are two safety measures commonly used in electric circuits.

Q20. An electric oven of 2 kW power rating is operated in a domestic electric circuit (220 V) that has a current rating of 5 A. What result do you expect? Explain.
Answer – Since, current drawn by the oven is greater than the rated value of current, which may cause overloading and excessive heating of the circuit.

21. What precaution should be taken to avoid the overloading of domestic electric circuits?
Answer –  The following precautions should be taken to avoid the overloading domestic electric circuits as given below:
(i) The circuits should be of proper current rating and appliances should be connected accordingly.
(ii) Wires should be checked from time to time those wires whose insulation is worn, should be immediately replaced.
(iii) Connection of too many appliances in a single socket must be avoided.




Exercise Questions – Magnetic Effects Of Electric Current – Chapter 13 (NCERT Solutions & All Extra And Important Questions) – Science (Class 10)

Q1.  Which of the following correctly describes the magnetic field near a long straight wire?
(a) The field consists of straight lines perpendicular to the wire.
(b) The field consists of straight lines parallel to the wire.
(c) The field consists of radial lines originating from the wire.
(d) The field consists of concentric circles centred on the wire.
Answer – (d) The magnetic field lines due to a straight current carrying wire are concentric circles with the centre on the wire.

Q2.  The phenomenon of electromagnetic induction is
(a) the process of charging a body.
(b) the process of generating magnetic field due to a current passing through a coil.
(c) producing induced current in a coil due to relative motion between a magnet and the coil.
(d) the process of rotating a coil of an electric motor.
Answer – (C) The process of producing induce current in a coil due to relative motion between a magnet and the coil is known as electromagnetic induction.

Q3. The device used for producing electric current is called a
(a) generator. (b) galvanometer. (c) ammeter. (d) motor.
Answer – (a) Generator converts mechanical energy to electrical energy.

Q4. The essential difference between an AC generator and a DC generator is that
(a) AC generator has an electromagnet while a DC generator has parmanent magnet.
(b) DC generator will generate a higher voltage.
(c) AC generator will generate a higher voltage.
(d) AC generator has slip rings while the DC generator has a commutator.
Answer – AC generator has slip rings while DC generator has split rings as commutator. Due to slip Rings the current produced by AC generator flows in both the direction while current produced by DC generator flows in single direction.

Q5. At the time of short circuit, the current in the circuit
(a) reduces substantially. (b) does not change. (c) increases heavily. (d) vary continuously.
Answer – (c) Increase heavily.

Q6.  State whether the following statements are true or false.
(a) An electric motor converts mechanical energy into electrical energy.
(b) An electric generator works on the principle of electromagnetic induction.
(c) The field at the centre of a long circular coil carrying current will be parallel straight lines.
(d) A wire with a green insulation is usually the live wire of an electric supply.
Answer – (a) False, electric motor converts electrical energy into mechanical energy.
(b) True,
(c) True,
(d) False, The wire with green insulation is the earth wire and not the live wire.

Q7. List two methods of producing magnetic fields.
Answer –  Three methods of producing magnetic field are as given below
(i). Passing Electric current through a straight conductor.
(ii). Passing Electric current through a circular loop.
(iii). Passing Electric current through a solenoid.

Q8. How does a solenoid behave like a magnet? Can you determine the north and south poles of a current–carrying solenoid with the help of a bar magnet? Explain.
Answer –  A solenoid behaves like a magnet when the electric current passes through it. 
One end of a solenoid behaves as a North Pole and the other end behaves as a South Pole. Use a bar magnet to determine the North and South poles of a current carrying solenoid by using the property, like poles repel and unlike poles attract each other. The end of the solenoid which attracts north pole of a bar magnet is magnetic South Pole of the solenoid. The end of the solenoid which repels the north pole of a bar magnet is the magnetic north pole of the solenoid.

Q9. When is the force experienced by a current–carrying conductor placed in a magnetic field largest?
Answer – The force experienced by a current carrying conductor placed in a magnetic field is the largest when the conductor is kept perpendicular to the direction of the magnetic field.

Q10. Imagine that you are sitting in a chamber with your back to one wall. An electron beam, moving horizontally from back wall towards the front wall, is deflected by a strong magnetic field to your right side. What is the direction of the magnetic field?
Answer – According to Fleming’s left-hand rule, the direction of magnetic field is vertically downward.




Q11. Draw a labelled diagram of an electric motor. Explain its principle and working. What is the function of a split ring in an electric motor?
Answer –

Q12. Name some devices in which electric motors are used.
Answer – Some Devices in which electric motors are used are electric fans, refrigerator, mixers, washing machines, computers etc.

Q13.  A coil of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is
(i) pushed into the coil, (ii) withdrawn from inside the coil, (iii) held stationary inside the coil?
Answer – The Galvanometer shows a deflection which means current is induced in the coil. Current is induced in the coil due to the relative motion between coil and magnet.
The Galvanometer shows a deflection in opposite direction which means current is induced in the opposite direction in this case the direction of motion is in the opposite direction w.r.t coil. There is no deflection in the Galvanometer has no current is induced in the coil this is because there is no relative motion between coil and magnet.

Q14.  Two circular coils A and B are placed closed to each other. If the current in the coil A is changed, will some current be induced in the coil B? Give reason.
Answer – Yes current will be induced in the coil B. When the current in the coil A is changed, The magnetic field around it changes. As the coils are close to each other the magnetic field around coil B changes and hence induces a current in coil B.

Q15. State the rule to determine the direction of a
(i) Magnetic field produced around a straight conductor-carrying current,
(ii) force experienced by a current-carrying straight conductor placed in a magnetic field which is perpendicular to it, and  (iii) current induced in a coil due to its rotation in a magnetic field.
Answer –

Q16. Explain the underlying principle and working of an electric generator by drawing a labelled diagram. What is the function of brushes?
Answer –

Q17. When does an electric short circuit occur?
Answer – An electric short circuit occurs when the insulation of wires is damaged or there is a fault in the appliance. Due to this the live and neutral wire come in direct contact and the current in the circuit increases abruptly.

Q18. What is the function of an earth wire? Why is it necessary to earth metallic appliances?
Answer – The earth wire is connected to a metallic plate buried deep inside the earth. In this way, the metallic body of the appliance is connected to the Earth, which provides a low resistance conducting path for electric current. Hence, Any leakage of current to the metallic body of the appliance to the earth through each wire. The use and might not get a severe electric shock on touching search and appliances in case of a fault




Examples Questions – Magnetic Effects Of Electric Current – Chapter 13 (NCERT Solutions & All Extra And Important Questions) – Science (Class 10)

Example 13.1 – A current through a horizontal power line flows in east to west direction. What is the direction of magnetic field at a point directly below it and at a point directly above it?
Solution – The current is in the east-west direction. Applying the right-hand thumb rule, we get that the magnetic field (at any point below or above the wire) turns clockwise in a plane perpendicular to the wire, when viewed from the east end, and anti-clockwise, when viewed from the west end.

Example 13.2 – An electron enters a magnetic field at right angles to it, as shown in Fig. 13.14. The direction of force acting on the electron will be (a) to the right. (b) to the left. (c) out of the page. (d) into the page.
Solution – Answer is option (d). The direction of force is perpendicular to the direction of magnetic field and current as given by Fleming’s left hand rule. Recall that the direction of current is taken opposite to the direction of motion of electrons. The force is therefore directed into the page.

 

Sources Of Energy – Chapter 14 (NCERT Solutions & All Extra And Important Questions) – Science (Class 10)

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SUBJECT – SCIENCE
CLASS – X (10th)
QUESTION FROM – Sources Of Energy – Chapter 14
ALL EXTRA & IMPORTANT / EXERCISE QUESTION ANSWER

Hi Friends, Welcome To – Study24Hours.Com, Here We Are Giving You Some Very Important Question & Answers From The Chapter Sources Of Energy – Chapter 14. Sources Of Energy Is The 14th Chapter Of Your Science NCERT Book Of Class X. So Check Out All Of Them & Please Revise All Of These Questions Before Your Exam. So Please Remember To Visit – www.Study24Hours.Com Daily For All Study Materials And More.

Sources Of Energy – Chapter 14 (NCERT Solutions) – Science (Class 10)

Intext Questions – Sources Of Energy – Chapter 14 (NCERT Solutions & All Extra And Important Questions) – Science (Class 10)

Q1. What is a good source of energy?
Answer – If a source of energy is easily accessible, easy to stored and transport has very good calorific value and available cheaply then it is a good source of energy. 

A good source of energy has following characteristics:-
(I) It could do a large amount of work per unit volume.
(ii) It should have high calorific value.
(iii) it should not leave behind any undesirable substance.
(iv) advanced easily in air at a moderate rate. 

Q2. What is a good fuel?
Answer – A good fuel is the one which burns completely without producing smoke or ash. It produces a large number of heat by burning a small quantity of it. It possesses all the characteristic of a good source of energy.

Q3. If you could use any source of energy for heating your food, which one would you use and why?
Answer – We would use an oven or heater to heat up food, instead of a stove or chulha. Because it heats the food faster, preserving the nutritional values of food.

Q4. What are the disadvantages of fossil fuels?
Answer – The disadvantages of fossil fuels are as follows:-
(I) it causes air pollution,
(ii) they earth formed under the Earth surface by a long process which takes millions of years to form.
(iii) it is a non renewable source of energy.
Sources Of Energy – Chapter 14 (NCERT Solutions) – Science (Class 10)
Q5. Why are we looking at alternate sources of energy?
Answer – We are looking at the alternative source of energy because the fossil fuels cannot be replenished back. Also, the rate at which we are using them will exhaust them soon. To meet the rising demand we have to use alternative sources of energy.

Q6. How has the traditional use of wind and water energy been modified for our convenience?
Answer – The windmills which have been traditionally used are converted to wind energy farms which contain a large
number of windmills to increase our energy output Hydropower plants are now associated with dams to produce electricity.



Q7. What kind of mirror – concave, convex or plain – would be best suited for use in a solar cooker? Why?
Answer – Concave mirror is best suited for use in a solar cooker. This is because it is a converging mirror and converges a large amount of light of the sun into the solar cooker.

Q8. What are the limitations of the energy that can be obtained from the oceans?
Answer –  The limitations of energy obtained from oceans are as given below,
(i) Locations, where dams can be built for tidal energy.
(ii) Wave energy is obtained only where waves are strong.
(iii) Efficient commercial exploitation of Ocean thermal energy is difficult.

Q9. What is geothermal energy?
Answer – Geothermal energy is the energy obtained from the hot spots in the earth’s crust. Underground water coming in contact with the hot spot, gets converted into steam and is trapped in rocks. This steam is routed through pipes to turbines and is used to generate electricity.

Q10. What are the advantages of nuclear energy?
Answer – Tremendous amount of energy is released during the nuclear reaction. This is much larger as compared to the same amount of any other fuel.

Q11. Can any source of energy be pollution-free? Why or why not?
Answer – No source of energy can be pollution free. Every time a source of energy exploited or used or consumed. It causes environmental pollution.

Q12. Hydrogen has been used as rocket fuel. Would you consider it a cleaner fuel than CNG? Why or why not?
Answer – Yes, because the burning of hydrogen releases water and burning of CNG produces carbon dioxide. This gas causes the greenhouse effect on the earth.

Q13. Name two energy sources that you would consider to be renewable. Give reasons for your choices.
Answer –  (i) Hydropower as water is replenished by the water cycle.
(ii) Wind power, as wind power keeps blowing due to uneven heating of the earth by the sun.

Q14. Give the names of two energy sources that you would consider to be exhaustible. Give reasons for your choices.
Answer – Fossil fuels like coal and petroleum are exhaustible. The condition that existed on the earth and led to their formation, no longer exist today. Thus, the rate at which they are used up today, will lead to their depletion soon.




Exercise Questions Answers – Sources Of Energy – Chapter 14 (NCERT Solutions & All Extra And Important Questions) – Science (Class 10)

Q1. A solar water heater cannot be used to get hot water on
(a) a sunny day. (b) a cloudy day. (c) a hot day. (d) a windy day.
Answer – (b) On a cloudy day there will be the least availability of solar energy. So, a solar heater will not work on that day. 

Q2. Which of the following is not an example of a biomass energy source?
(a) Wood (b) Gobar-gas (c) Nuclear energy (d) Coal
Answer – (c) Nuclear energy is not an example of biomass energy source.

Q3. Most of the sources of energy we use represent stored solar energy. Which of the following is not ultimately derived from the Sun’s energy?
(a) Geothermal energy (b) Wind energy (c) Nuclear energy (d) Biomass.
Answer – Nuclear energy is the only energy which is ultimately derived from the sun’s energy.

Q4. Compare and contrast fossil fuels and the Sun as direct sources of energy.
Answer – The difference between fossil fuels and the sun are given below,
Fossil Fuels
(i). These non-renewable sources.
(ii) These are exhaustible sources.
(iii) These cause environmental pollution.
(iv) These are expensive.
(v) These have to be extracted for use.
Sun
(i) It is a renewable source.
(ii) It is a non-exhaustible source.
(iii) It is a non-polluting source.
(iv) it is not expensive but setting of devices such as a “solar cell” is costly. (One-time investment)
(v) It is more easily available.

Q5. Compare and contrast bio-mass and hydroelectricity as sources of energy.
Answer – The similarity between both is that they are a renewable source of energy. The differences between biomass and hydroelectricity are given below,
Bio-Mass
(i) The residue is used as manure,
(ii) It is less expensive.
(iii) It helps in the disposal of organic waste.
Hydroelectricity
(i) No residue is left.
(ii) It is expensive in terms of construction of dams.
(iii) It does not produce any organic waste.




Q6. What are the limitations of extracting energy from – (a) the wind? (b) waves? (c) tides?
Answer – This Answer will be added soon!

Q7. On what basis would you classify energy sources as
(a) renewable and non-renewable?
(b) exhaustible and inexhaustible? Are the options are given in (a) and (b) the same?
Answer –
(a) renewable and non-renewable?
I. The sources of energy which can be replenished in a short time are called renewable resources. The sources of energy which take a long time to replenish what do not replenish are non-renewal resources.
(b) exhaustible and inexhaustible? Are the options are given in (a) and (b) the same?
II. the sources of energy which are limited and may get exhausted are exhaustible source. 2 sources of energy recharge unlimited and will never get exhausted are inexhaustible source. Renewable sources are inexhaustible sources, wild, not renewable sources are exhaustible sources.

Q8. What are the qualities of an ideal source of energy?
Answer – An ideal source of energy has the following qualities,
(i) Production of a large amount of heat energy,
(ii) Easily accessible,
(iii) Easy to store within the space,
(iv) Easy to transport,
(v) Possibly inexhaustible cost-effective fuel,
(vi) No production of toxic byproducts
(vii) Not pollute the environment.

Q9. What are the advantages and disadvantages of using a solar cooker? Are there places where solar cookers would have limited utility?
Answer –
Advantages:-

i. It is easy to handle a solar cooker.
ii. The nutrients of food do not get destroyed.
iii. Cooks food without causing any pollution.
iv. It is economical to use a solar cooker. 
Disadvantages:-
1. solar energy is not available at all time and at all the place.
2. It cannot be used at night and in cloudy day.
3. It cannot be used for baking and frying purpose.
4. It takes more time to cook food.
5. the direction of solar cooker is to be changed continuously towards the direction of sun.
Sources Of Energy – Chapter 14 (NCERT Solutions) – Science (Class 10)

Q10. What are the environmental consequences of the increasing demand for energy? What steps would you suggest to reduce energy consumption?
Answer – Increasing demand for energy is adversely affecting our environment in the following ways,

I. Extraction of resources from nature disturbs many natural cycles and also cause air pollution.
II. Use of energy sources and disposal of end products into the air, water and soil causes production.
III. Greenhouse effect is caused by pouring of gaseous toxins into the air. This has resulted in global warming.
IV. Cutting of trees results in soil erosion, floods etc.
(a) Using environment-friendly fuels such as biogas and CNG etc,
(b) Planting more trees,
(c) Encouraging the recycling of materials,
(d) Properly disposing off garbage,
(e) Using biodegradable substances over plastic.

Sources Of Energy – Chapter 14 (NCERT Solutions) – Science (Class 10)

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Our Environment – Chapter 15 (NCERT Solutions & All Extra And Important Questions) – Science (Class 10)

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SUBJECT – SCIENCE
CLASS – X (10th)
QUESTION FROM – Our Environment – Chapter 15
ALL EXTRA & IMPORTANT / EXERCISE QUESTION ANSWER

Hi Friends, Welcome To – Study24Hours.Com, Here We Are Giving You Some Very Important Question & Answers From The Chapter Our Environment – Chapter 15. Our Environment Is The 15th Chapter Of Your Science NCERT Book Of Class X. So Check Out All Of Them & Please Revise All Of These Questions Before Your Exam. So Please Remember To Visit – www.Study24Hours.Com Daily For All Study Materials And More.




INTEXT QUESTIONS – Our Environment – Chapter 15 (NCERT Solutions & All Extra And Important Questions) – Science (Class 10)

Q1. What are trophic levels? Give an example of a food chain and state the different trophic levels in it. (Page – 260)
Answer – The transfer of food or energy takes place through various levels in the food chain, which are known as trophic levels for example, (Trees ⟩⟩ Rabbit ⟩⟩ Snakes ⟩⟩ Hawk)

Q2. What is the role of decomposers in the ecosystem? (Page – 260)
Answer – Organism that feeds on dead plants and animals are called decomposers. Eg. Bacteria fungi etc. The breakdown the complex organic compounds present in the dead remains into simpler substances and obtain nutrition from them. The substances are released into the soil and the atmosphere.

Q3.  Why are some substances biodegradable and some non-biodegradable? (Page – 262)
Answer – Certain substances are easily acted upon by the enzymes of saprophytes and get converted into simpler substances, hence are biodegradable. Whereas certain substances like plastic, etc., cannot be degraded by the action of enzymes and thus, are called non-biodegradable.

Q4. Give any two ways in which biodegradable substances would affect the environment? (Page – 262)
Answer – The two ways in which biodegradable substances would affect the environment are:
(i) Their degradation may release certain gases in the atmosphere thereby, polluting the environment.
(ii) They may become breeding places of flies and many other pests, thus causing diseases.

Q5. Give any two ways in which non-biodegradable substances would affect the environment? (Page – 262)
Answer – The two ways in which non-biodegradable substances would affect the environment are:
(i) They make the environment poisonous and unfit for the survival of living forms of life.
(ii) They block the transfer of energy and minerals in the ecosystem. 

Q6. What is ozone and how does it affect any ecosystem? (Page – 264)
Answer – Ozone is a triatomic molecule i.e made up of 3 atoms of oxygen join together. Its molecular formula is O3.
It can affect any ecosystem in the following ways :
(i) It protects against ultraviolet rays if, the present is stratosphere.
(ii) Ozone dissipates the energy of UV rays by undergoing dissociation followed reassociation.
2O3 —> 3O2 + Energy
(iii) In the atmosphere, it is highly toxic and causes injury to mucous membranes, eye irritation and internal haemorrhages in animals and humans.

Q7. How can you help in reducing the problem of waste disposal? Give any two methods. (Page – 264)
Answer – Answer will be added soon.




NCERT EXERCISE QUESTIONS –  Our Environment – Chapter 15 (NCERT Solutions & All Extra And Important Questions) – Science (Class 10)

Q1. Which of the following groups contain only biodegradable items?
(a) Grass, flowers and leather
(b) Grass, wood and plastic
(c) Fruit-peels, cake and lime-juice
(d) Cake, wood and grass
Answer – Answer will be added soon.

Q2. Which of the following constitute a food-chain?
(a) Grass, wheat and mango
(b) Grass, goat and human
(c) Goat, cow and elephant
(d) Grass, fish and goat
Answer – Answer will be added soon.

Q3. Which of the following are environment-friendly practices?
(a) Carrying cloth-bags to put purchases in while shopping
(b) Switching off unnecessary lights and fans
(c) Walking to school instead of getting your mother to drop you on her scooter
(d) All of the above
Answer – Answer will be added soon.

Q4. What will happen if we kill all the organisms in one trophic level?
Answer – If we kill all the organisms in one trophic level, the lower trophic level will grow more in number and the higher trophic level will not survive. Hence, the flow of energy from one trophic level to other will not take place.

Q5. Will the impact of removing all the organisms in a trophic level be different for different trophic levels? Can the organisms of any trophic level be removed without causing any damage to the ecosystem?
Answer – (I) Yes, the impact of removing all the organism in a trophic level will be different for different trophic levels. The lower tropic level of an ecosystem has a greater number of individuals then the higher trophic levels. Removal of the producer will affect all the organism of successive trophic level and it will threaten their survival. The removal of the higher trophic level will lead to an increase in an organism of the lower trophic level and the organism of the higher trophic level will die due to the shortage of food.

(II) No removal of all organism of it tropic level will disturb the ecosystem killing of the higher trophic level organism will cause an explosion in the population of the lower level organism will cause an explosion in the population of the level organism. This will adversely affect the ecosystem.

Q6. What is biological magnification? Will the levels of this magnification be different at
different levels of the ecosystem?
Answer – Biological magnification refers to the increase in the concentration of certain toxicants at each successive trophic level. No, the levels of magnification will not be same in all trophic levels. When the chemical does not get degraded and get accumulated progressively at each trophic level, it leads to biomagnification. Biomagnification is more in an organism of higher trophic level.

Q7. What are the problems caused by the non-biodegradable wastes that we generate?
Answer – Answer will be added soon.

Q8. If all the waste we generate is biodegradable, will this have no impact on the
environment?
Answer –  If all the waste is biodegradable, then there will be no accumulation of waste and the Earth would be a cleaner place to live. But if this biodegradable waste is too large in amount then its slow degradation may lead to air pollution (due to the release of gases) as well as water and land pollution.Q9. Why is damage to the ozone layer a cause for concern? What steps are being taken
to limit this damage?
Answer – Thinning of ozone layer present in the stratosphere is called depletion of the ozone layer. Due to depletion of ozone layer, harmful ultraviolet radiations can reach the surface of Earth, which may lead to skin diseases, cancer, etc. To reduce the depletion of the ozone layer, the use of chlorofluorocarbons has been minimised. In 1987, the UNEP has passed an agreement to freeze CFC production at 1986 levels.

 

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Management Of Natural Resources – Chapter 16 (NCERT Solutions & All Extra And Important Questions) – Science (Class 10)

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SUBJECT – SCIENCE
CLASS – X (10th)
QUESTION FROM – Management Of Natural Resources – Chapter 16
ALL EXTRA & IMPORTANT / EXERCISE QUESTION ANSWER

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INTEXT QUESTIONS – Management Of Natural Resources – Chapter 16 (NCERT Solutions & All Extra And Important Questions) – Science (Class 10)

Q1. What changes can you make in your habits to become more environment-friendly? (Page 271)
Answer – We should try and know about how our choices of using natural resources affect the environment. Use of using renewable resources and biodegradable stuff should be promoted, e.g.
(I) Use of paper bags instead of plastic.
(ii) Use of energy sources like LPG, solar energy, which do not cause pollution.
(iii) Use of substances which can be recycled or can be reused.

Q2. What would be the advantages of exploiting resources with short-term aims? (Page 271)
Answer – Exploiting natural resources with short term aims has some advantages. First of all, it takes millions of years for the formation of natural resources and it is not possible to renew them.
Hence, the aims with long termed perspective is that these resources must last for the generations to come. For this, short term aim must be avoided. Our current basic needs can be fulfilled only by awareness.
The expenditure for short term requirements will be less and there will be full utilisation of resources and the wastage will be very low

Q3. How would these advantages differ from the advantages of using a long-term perspective in managing our resources? (Page 271)
Answer –  

Q4. Why do you think that there should be an equitable distribution of resources? 
What forces would be working against an equitable distribution of our resources? (Page 271)
Answer – There should be the equitable distribution of resources among all people rich and poor so that all benefited from the development of these resources.
Such an even distribution of resources restrict the exploitation, wastage and misuse of these resources. The poor will also get a chance to get the benefit for himself and this way the society will improve. Unfortunately, it has been observed that mainly the rich and the powerful take the full advantage of these resources and the poor are devoid of its pleasure. Thus, the use of resources by rich and powerful people for their personal benefit work against the equitable distribution.

Q5. Why should we conserve forests and wildlife? (Page 275)
Answer – We must conserve our forest as they are of Great value because,
I) forest help in the production of land and retaining subsoil water.
II) what is check floods and maintain the ecosystem.
Why life is important for us because,
I) they provide create an aesthetic value of human beings,
II) they help in maintaining ecological balance.

Q6. Suggest some approaches towards the conservation of forests? (Page 275)
Answer – Various approaches are required for the conservation of forests. Afforestation is one of the most important approaches.
Besides this approach, the following steps should be taken:
(i) Deforestation should be banned.
(Ii) People should be made more aware of the importance of forests.
(ii) The protected areas should be managed by local people which would be quiet efficient.
(iv) National parks and sanctuaries should be formed to conserve the biodiversity.
(v) Hunting should be banned and laws should be formulated against hunting.
(vi) There should be proper laws for the exploitation of forest resources.

Q7. Find out about the traditional systems of water harvesting/ management in your region? (Page 278)
Answer – There are many traditional methods of water harvesting or management. these are khadin, ponds, tala etc. Also, wells have been dugged for drinking water and irrigation purpose. Canon has been developed and water reservoirs are made by the government for providing proper drinking water.

Q8. Compare the above system with the probable systems in hilly/ mountainous areas or plains or plateau regions. (Page 278)
Answer – In hilly or mountains areas most of the rainwater flows fast downwards and thus, people have more opportunity of water harvesting well in plains and plateau, the water flows with slow speed and most of it is for percolated down in the soil.

Q9. Find out the source of water in your region/locality. Is water from this Is source available to all people living in that area? (Page 278)
Answer – There are mainly two sources of water in our locality Handpump and municipality supply.
The water from a hand pump is available to all people but access to municipality water is restricted to developed colonies only.

NCERT EXERCISE QUESTIONS –  Management Of Natural Resources – Chapter 16 (NCERT Solutions & All Extra And Important Questions) – Science (Class 10)




Q1. What changes would you suggest in your home in order to be environment-friendly?
Answer – Certain changes can be incorporated in our daily routine at home to make it more eco-friendly.
(I) We should plant different kinds of shady plants, fruit and vegetable bearing trees.
(ii) We should use water and electricity efficiently in routine activities.
(iii) Food should be properly stored to avoid any spoilage, thereby preventing its wastage.
(iv) There should be a proper drainage system for the water to pass in the drains.
(v). That should be proper disposal of water.
(vi) Dustbins and other waste product should be properly covered and the garbage be dumped around the houses.

 

Q2. Can you suggest some changes to your school which would make it environment-friendly?
Answer –  (I) to make our school environment-friendly it is essential to plan different kinds of shady and fruity trees. The different flowering plant should also be planted.
(ii) Waste material such as used paper for oil empty packet should be properly thrown into the dustbin.

 

Q3. We saw in this chapter that there are four main stakeholders when it comes to forests and wildlife. Which among these should have the authority to decide the management of forest produce? Why do you think so?
Answer – Out of the four categories of stakeholders, the local people living around the forest areas should be given the authority to decide the management of forest produce. This is because the traditional method of exploitation of natural resources employed by the local people ensure that the sustainable of resources is maintained and they remain conserved in sufficient amount to meet the needs of future generation.
Their traditional methods ensure the recovery and regrowth of resources after they have used them, e.g. in the reserved area of great Himalayan National Park, when nomadic shepherds were allowed to graze their sheep in the alpine meadows during summers, the grass regrew naturally after grazing.
But, without the regular grazing by sheep today in that area, the grass first grows very tall and then falls over there, preventing fresh growth. There are also some examples of local people that have been working traditionally for the conservation of forests like Bishnoi community in Rajasthan. So, I think nobody can manage the use of forest resources as efficiently as the local people can do.

 

Q4. How can you as an individual contributor or make a difference to the management of (a) forests and wildlife, (b) water resources and (c) coal and petroleum?
Answer – 
(i) Forest & Wildlife
(a) We should judiciously use the forest products.
(b) Cutting of trees for paper, timber, etc., should be So controlled.
(C) The killing of wild animals for their skin, horns, etc., should be banned.
(d) Afforestation should be practised.
(e) Management of the forest should be given to local people.
(ii) Water resources
(a) Leaking taps should be repaired.
(b) Water from industries should not be directly dumped in the river water, thus reducing water
pollution.
(c) Use of insecticides and pesticides should be minimised, which are usually washed away with
rain. They contaminate river water and underground water.
(d) Methods like rainwater harvesting, construction of canal should be promoted. Construction of
dams may also prove beneficial,
(iii) Coal & Petroleum

(a) Use of coal and petroleum as a source of energy should we minimise should be promoted
should be minimised should be promoted.
(b) Use of CNG or LPG as fuels in automobiles
should be promoted.
Q5. What can you as an individual do to reduce your consumption of the various natural resources?
Answer – The following activities can help in reducing the consumption of various natural resources:

(I) Use of solar cooker and minimum use of cooking gas.
(ii) Closing all taps when not in use.
(iii) Switching off electric appliances when not in use.
(iv) Making minimum use of auto-vehicles and more of public transport vehicles.
(v) Minimum use of air conditioners.
(vi) Avoid wastage of food.

 

Q6. List five things you have done over the last one week to —
(a) conserve our natural resources.
(b) increase the pressure on our natural resources.
Answer –
(i) conserve our natural resources.
(a) Limited use of water
(b) Plantation in free areas
(c) Irrigation of plants
(d) Limited use of petrol/diesel
(e) Smokeless fuel utilisation
(ii) increase the pressure on our natural resources.
(a) Extra use of water
(b) Day and night lighting
(c) Unnecessary traffic due to use of car
(d) Burning of polythene and wastes
(e) Destroying the plants

 

Q7. On the basis of the issues raised in this chapter, what changes would you
incorporate in your lifestyle in a move towards sustainable use of our resources?
Answer – On the basis of issues raised in this chapter, we would
Incorporate the 3 Rs in our lifestyle and a move towards limited use of petrol/diesel, water conservation, more
plantation, use of LPG in homes, use of biodegradable products, etc. We will work towards sustainable utilisation of resources.

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Chemical Reactions And Equations – Chapter 1 (NCERT Solutions & All Extra And Important Questions) – Science (Class 10)

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SUBJECT – SCIENCE
CLASS – X (10th)
QUESTION FROM – Chemical Reactions And Equations – Chapter 1
ALL EXTRA & IMPORTANT / EXERCISE QUESTION ANSWER

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INTEXT QUESTIONS – Chemical Reactions And Equations – Chapter 1 (NCERT Solutions & All Extra And Important Questions) – Science (Class 10)

Q1. Why is the amount of gas collected in one of the test tubes in activity 1.7 (electrolysis of water
double of the amount collected in the other? Why should a magnesium ribbon be cleaned before burning in air?
Answer – Magnesium ribbon reacts with oxygen present in air to form a protective and inert layer of magnesium oxide on its surface. This layer is unreactive and prevents the ribbon from burning. Hence, it needs to be cleaned with sand paper before burning in air.

 

Q2. Write the balanced equation for the following chemical reactions :-
(i) Hydrogen + Chlorine —> Hydrogen chloride
(i) Barium chloride + Aluminium sulphate —> Barium sulphate +Aluminium chloride
(iii) Sodium + Water —> Sodium Hydroxide + Hydrogen
Answer – (I) H2+Cl2 —> 2HCl
(ii) 3BaCl2 + Al2(SO4)3 —> 3BaSO4 + 2AlCl3
(iii) 2Na + 2H2O —> 2NaOH + H2

 

Q3. Write a balanced chemical equation with state symbols for the following reactions.
(i) Solutions of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride.
(ii) Sodium hydroxide solution (in water) reacts with hydrochloric acid solution (in water) to produce sodium chloride solution and water.
Answer – (I) BaCl2(aq) + Na2SO4(aq) —> BaSO4(s) + 2NaCl(aq)
(II) NaOH(aq) + HCl (aq) —> NaCl (aq) + H2O (l)

 

Q4. A solution of a substance ‘X’ is used for white washing.
(i) Name the substance ‘X’ and write its formula.
(i) Write the reaction of the substance ‘X’ named in
 (I) above with water.
Answer – (i) Substance X is calcium oxide or quicklime. Its Formulae is CAO.
(II) Quicklime reacts with water as :- CaO (s) + H2O (l) —> Ca(OH)2 (aq)

 

Q5. Why is the amount of gas collected in one of the test tubes in Activity 1.7 double of the amount collected in the other? Name this gas.
Answer –  The composition of water, i.e. the chemical formula H.O, suggests that the molar ratio of hydrogen and oxygen is 2 : 1. Therefore, when water is electrically decomposed, the constituent gases hydrogen and oxygen are produced in the same molar ratio, 2 : 1. Thus, the amount (volume) of hydrogen gas is double than that of oxygen gas. So, this gas is hydrogen.

 

Q6. Why does the colour of copper sulphate solution change when an iron nail is dipped in it ?
Answer – The colour of copper sulphate solution changes when an iron nail is dipped in it because iron being more reactive than copper, displaces copper metal from aqueous copper sulphate solution. Thus, blue colour of copper sulphate fades away to give green colour solution of ferrous sulphate.
Fe (s) + CuSO4 (aq) —> FeSO4 (aq) + Cu (s)

 

Q7. Give an example of a double displacement reaction other than the reaction of barium chloride with sodium sulphate ?
Answer – The following reaction is an example of a double displacement reaction :
2Naoh (aq) + H2SO4 (aq) —> Na2So4 + 2H2O (l)

 

Q8. Identify the substances that are oxidised and the substances that are reduced in the following reactions.
(i) 4Na(s) + O2(g) → 2Na2O(s)
Answer – Na has gained oxygen and forms Na2O. So, Na is oxidised and O2 is reduced.
(ii) CuO(s) + H2(g) → Cu(s) + H2O(l) 
Answer – CuO has lost oxygen and forms Cu. So, Cu is reduced while H2 has gained oxygen, hence, its oxidised.




EXERCISE QUESTIONS – Chemical Reactions And Equations – Chapter 1 (NCERT Solutions & All Extra And Important Questions) – Science (Class 10)

Q1. Which of the statements about the reaction below are incorrect? 2PbO(s) + C(s) → 2Pb(s) + CO2 (g)
(a) Lead is getting reduced.
(b) Carbon dioxide is getting oxidised.
(c) Carbon is getting oxidised.
(d) Lead oxide is getting reduced.
Answer – The given reaction can be written in the form of two separate reaction :-
2PbO (s) —–> 2Pb (s)
C (s) —-> CO2(g)
Therefore, (I) and (ii) are incorrect, And (iii) and (iv) are correct statements.

 

Q2. Fe2O3 + 2Al → Al2O3 + 2Fe The above reaction is an example of a :-
(a) combination reaction.
(b) double displacement reaction.
(c) decomposition reaction.
(d) displacement reaction.
Answer – (iv) In the above reaction, Al is more reactive than Fe. So, it displaces Fe frpm Fe2O3 to form Al2O3. It is a displacement reactions.


Q3. What happens when dilute hydrochloric acid is added to iron fillings? Tick the correct answer.
(a) Hydrogen gas and iron chloride are produced.
(b) Chlorine gas and iron hydroxide are produced.
(c) No reaction takes place.
(d) Iron salt and water are produced. 
Answer – Iron being more reactive than hydrogen, displaces hydrogen from the dilute hydrochloric acid. Thus, hydrogen gas and iron chloride a salt of iron are formed.
Fe(s) + 2HCl (aq) —> FeCl2 (aq) + H2(g)


4. What is a balanced chemical equation? Why should chemical equations be balanced ?
Answer – A chemical change is represented by a chemical equation. When the number of atoms of different elements on reactant and product side are equal, then the chemical equation is called a balanced chemical equation.
It is important to balance a chemical equation because
(1) to validate the law of conservation of mass which states that the mass of reactants should be equal to the mass of the products. The total mass of a system is thus conserved. This law holds true only if number of atoms of reactants reacting together is equal to number of product atoms formed.
(2) a balanced chemical equation tells us about the physical state of the reactants and products whether they are solid (s), liquid (l) or gas (g) or aqueous (ag)
(3) it tells us about heat changes that can take place in a chemical reaction. A is the symbol of heat.
Hence, it is endothermic or exothermic can be deduced from a balanced chemical equations.


Q5. Translate the following statements into chemical equations and then balance them.
(a) Hydrogen gas combines with nitrogen to form ammonia.
(b) Hydrogen sulphide gas burns in air to give water and sulpur dioxide.
(c) Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate.
(d) Potassium metal reacts with water to give potassium hydroxide and hydrogen gas. 
Answer – 


Q6.  Balance the following chemical equations.
(a) HNO3 + Ca(OH)2 → Ca(NO3)2 + H2O
(b) NaOH + H2SO4 → Na2SO4 + H2O
(c) NaCl + AgNO3 → AgCl + NaNO3
(d) BaCl2 + H2SO4 → BaSO4 + HCl
Answer – 


Q7. Write the balanced chemical equations for the following reactions.
(a) Calcium hydroxide + Carbon dioxide → Calcium carbonate + Water
(b) Zinc + Silver nitrate → Zinc nitrate + Silver
(c) Aluminium + Copper chloride → Aluminium chloride + Copper
(d) Barium chloride + Potassium sulphate → Barium sulphate + Potassium chloride
Answer – 


Q8. Write the balanced chemical equation for the following and identify the type of reaction in each case.
(a) Potassium bromide(aq) + Barium iodide(aq) → Potassium iodide(aq) + Barium bromide(s)
(b) Zinc carbonate(s) → Zinc oxide(s) + Carbon dioxide(g)
(c) Hydrogen(g) + Chlorine(g) → Hydrogen chloride(g)
(d) Magnesium(s) + Hydrochloric acid(aq) → Magnesium chloride(aq) + Hydrogen(g)
Answer – Write the balanced chemical equation for the following and identify the type of reaction in each case. (a) Potassium bromide(aq) + Barium iodide(aq) → Potassium iodide(aq) + Barium bromide(s) (b) Zinc carbonate(s) → Zinc oxide(s) + Carbon dioxide(g) (c) Hydrogen(g) + Chlorine(g) → Hydrogen chloride(g) (d) Magnesium(s) + Hydrochloric acid(aq) → Magnesium chloride(aq) + Hydrogen(g)


Q9. What does one mean by exothermic and endothermic reactions? Give examples.
Answer –  What does one mean by exothermic and endothermic reactions? Give examples.






Q10. Why is respiration considered an exothermic reaction? Explain.
Answer – 


Q11. Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions.
Answer – 

In a decomposition reaction, single reactant breaks down to produce two or more products, whereas in a combination reaction, two or more reactants combine to give a single product. Thus, these reactions are supposed to be opposite of each other, e.g.Explain the following terms with one example each. (a) Corrosion (b) Rancidity


Q12. Write one equation each for decomposition reactions where energy is supplied in the form of heat, light or electricity.
Answer – Write one equation each for decomposition reactions where energy is supplied in the form of heat, light or electricity.


Q13. What is the difference between displacement and double displacement reactions? Write equations for these reactions.
Answer – In a displacement reaction, a more reactive element displaces a less reactive element from its salt solution. But in a double displacement reaction, two atoms or groups from different compounds displace each other.
Chemical equation for single displacement,
Zn (s)+ CuSO4(aq) —> ZnSO4(aq) + Cu(s)
Here, Zn displaces Cu from its salt solution (CuSO4).
Chemical equation for double displacement,
BaCI2(aq) + K2SO(a) —> BaSO4(s)+ 2KCI(aq)
Here, Ba and K displace each other.


Q14. In the refining of silver, the recovery of silver from silver nitrate solution involved displacement by copper metal. Write down the reaction involved.
Answer – The reaction involved is : 
2AgNO3(aq) + Cu(s) —-> Cu(NO3)2(aq) + 2Ag(s)


Q15. What do you mean by a precipitation reaction? Explain by giving examples ?
Answer –The reaction which is accompanied by the formation of an insoluble solid mass (called precipitate) is known as precipitation reaction, e.g.
1) When barium chloride solution is added to an aqueous solution of sodium sulphate, a white precipitate of barium sulphate is obtained
BaCl2(aą) + Na2SO4 (aq) —> BaSO4(s) 2NaCl (aq)
2) When silver nitrate is added to an aqueous solution of sodium chloride, a white precipitate
of silver chloride (AgCI), which is soluble in
NH4OH is obtained.
AgNO3 (ag) + NaCl(aą) → AgCl(s) ↓ + NaNO3 (aq)


Q16. Explain the following in terms of gain or loss of oxygen with two examples each.
(a) Oxidation (b) Reduction
Answer –


Q17. A shiny brown coloured element ‘X’ on heating in air becomes black in colour. Name the element ‘X’ and the black coloured compound formed?
Answer  – Element X is copper and the black coloured compound is copper (II) oxide.
2Cu(s) + O2(g) —–> 2CuO(s)


Q18.  Why do we apply paint on iron articles? 
Answer – By applying paint on iron articles, they can be prevented from corrosion (rusting). Paint does not allow oxygen (from air) and water to come in contact with the surface of iron.


Q19. Oil and fat containing food items are flushed with nitrogen. Why?
Answer – Nitrogen is unreactive gas as compared to oxygen. Oil and fat present in the food items get oxidised and become rancid in the presence of air or oxygen. But such reaction is prevented in the
presence of nitrogen. Therefore, food items like potato chips etc., are packed with nitrogen gas to prevent them from rancidity for a long time.


Q20. Explain the following terms with one example each. (a) Corrosion (b) Rancidity.
Answer – (A) Corrosion – This process is commonly known as rusting of iron. Some other metals also get tarnished in this manner. When a metal is attacked by substances around it such as moisture, acids, etc., it is said to corrode and this process is called corrosion. The black coating on silver and the green coating on copper are other examples of corrosion.
(B) Rancidity – When fats and oils are oxidised, they become rancid and their smell and taste change.

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Science – Chapter 2 (Acids, Bases And Salts) Important Questions For 2019 Board Exams – Class 10

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SUBJECT – SCIENCE (CHEMISTRY)
CLASS – X (10th)
QUESTION FROM – ACID, BASES AND SALTS (Chapter 2)
ALL EXTRA & IMPORTANT QUESTION ANSWER FOR 2019 EXAMS

Science – Chapter 2 (Acids, Bases And Salts) Important Questions For 2019 Board Exams – Class 10

Q1. Why does phenolphthalein consider as acid base indicator ? [2]
Ans – It is because it turns pinks in basic solutions while it remains colourless in acidic and neutral solutions. It is able to differentiate acids and bases. 


Q2. Name a salt of strong acid HNO3 and a weak base like NH4OH. Represent the reactions that takes place ? [1]
Ans – The salt that forms due to the below reactions is Ammonium nitrate (NH4NO3). The reactions is represented as :- HNO3 + NH4OH —> NH4NO3

Q3. When is acetic acid called a weak acid through there are 4’H’ atoms in the molecules ? [1]
Ans – Acetic acid is called a monobasic acid because only one of the 4’H’ atoms of the acid get released as H+ ion in solution. 

Q4. (a) Why does acidic solutions conduct electricity ? [1]
(b) Can basic solutions conduct electricity ? [1]
(c) Can separation of H+ ions in acidic takes place when HCL is added to a non-aqueous solution ? [1]
Ans – (a)  Due to the presence of ions (H+ ions and its counter ions) they conduct electricity.
(b) Yes, basic solutions conduct electricity.
(c) No, there will not be any dissociation of HCL in non-aqueous solution.

Q5. When acid reacts with bases, what types of compounds forms ? [1]
Ans – When acid reacts with bases then Salts and water forms.

Q6. Solution P has a pH of 13, solution Q has a pH of 6 and solution R has a pH of 2. {2}
(a) Which solution will be liberate Ammonia from Ammonia sulphate ?
(b) Which solution is a strong acid ?
Ans – (a) Solution P.
(b) Solution R.

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Science Important Topics – Important Questions For 2019 Board Exams – Class 10

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SUBJECT – SCIENCE (CHEMISTRY)
CLASS – X (10th)
QUESTION FROM – Science Important Topics For 2019 Board Exams
ALL EXTRA & IMPORTANT TOPICS FOR 2019 EXAMS – SCIENCE

Science Important Topics – Important Questions For 2019 Board Exams – Class 10 (CBSE & All State Boards Questions)

Q1. Magnetic Effect Of Electric Current. (विधुत चुम्बकीय प्रभाव)

Q2. Magnetic Field Lines. (चुम्बकीय छेत्र रेखाएं)

Q3. Right Hand Rule. (फ्लेमिंग का दछिन हस्त नियम)

Q4. Left Hand Rule. (फ्लेमिंग का वाम हस्त नियम)

Q5. Short Circuit. (लघुपथन)

Q6. Over Loading. (अतिभारण)

Q7. Electric Fuse & Working. (विधुत फ्यूज़)

Q8. Maxwel’s Right Hand Rule. (मैक्सवेल का दछिन हस्त नियम)

Q9. Ohm’s Law – (ओम का नीयम) – Watch Video

Q10. Electric Motor – (विधुत मोटर) – Watch Video

Q11. Generator – 

Q12. Neuron – 

Q13. Human Digestion – (मानव मे पोषण की प्रक्रिया) – Watch Video

Q14. Human Eye – (मानव नेत्र, नेत्र गोलक) – Watch Video

Click Here To Download >> Answer Key For These Questions !!

Science Important Topics - Important Questions For 2019 Board Exams – Class 10
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Science – Chapter 1 (Chemical Reactions And Equations) Important Questions For 2019 Board Exams – Class 10

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SUBJECT – SCIENCE (CHEMISTRY)
CLASS – X (10th)
QUESTION FROM – CHEMICAL REACTIONS & EQUATIONS
ALL EXTRA & IMPORTANT QUESTION ANSWER FOR 2019 EXAMS

Science – Chapter 1 (Chemical Reactions And Equations) Important Questions For 2019 Board Exams – Class 10 (CBSE & All State Boards Questions)

Q1. What is meant by thermal decomposition ? (1)
Answer – It is defined as the decomposition of chemical compounds after absorption of heat.

Q2. How does the food become rancid ? (1)
Answer – Food becomes rancid when fat and oils present in the food get oxidized.

Q3. On what chemical law, balancing of chemical equations is based ? (1)
Answer – Balancing of chemical equation is based on the law of conservation of mass.

Q4. What is lime -water test for the detection of carbon dioxide ? (2)
Answer – When carbon dioxide gas passes through lime water it turns milky due to the formation of milky suspension (precipitate) of calcium carbonate. Carbon dioxide is produced by the action of dilute HCl on sodium carbonate.

Q5. A copper coin is kept in a solution of silver nitrate for some time. What will happen to the coin and the colour of the solution ? (2)
Answer – We know that copper is more reactive than silver, so it will displace silver from its salt solution – Cu(S)+2AgNO3(aq) –> Cu(NO3)2(aq) + 2Ag(s)

Q6. (A) Why can a chemical change not be normally reversed ? (1)
Answer – In chemical change some bonds breaks and some bonds form. The products are quite different from the reactants. Therefore normally some chemical reactions can’t be reversed.

(B) Why does AgCI keep in dark place ? (1)
Answer – Because in presence of sunlight it decomposes.

(C) Represent decomposition of ferrous sulphate with the help of balanced chemical equation. (1)
Answer – 2FeSO4(s) –> Fe2O3(s)+SO2(g)+SO3(g)

(D) Can rusting of iron take place in distilled water ? (1)
Answer – No rusting of iron cannot take place in distilled water because it neither contains dissolved oxygen nor CO2, both are essential for rusting of iron.

(E) Name the chemical present in photographic film ? (1)
Answer – AgBr.

Science - Chapter 1 (Chemical Reactions And Equations) Important Questions For 2019 Board Exams - Class 10
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For More Questions And Answers, Please Use Our Search Option To Search Those Answers. Please Keep Visiting – www.Study24Hours.Com For More Study Materials. Thank You For Visiting This Site !!