a) Both assertion and reason are true and reason is correct explanation of assertion.

(b) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion

In exhaustible

Neural damage

It refers to afforestation programmes which includes planting and protecting trees with multiple uses and helps in restoration of green cover.

(i) It means a world which should last forever.
(ii) The global resources must be shared by living organisms judiciously

(i) Prohibit killing and hunting of specified animals.
(ii) Constitute sanctuaries, national parks, and closed areas for wild life conservation.

(i) Coal is used to generate electricity. If electricity is saved it will in turn reduce the use of coal.
(ii) Using bicycle for covering short distances instead of using cars, scooters or motorcycles.

Hydropower plants converts the kinetic energy of flowing water into electricity. This is called hydroelectricity.

Biogas is the mixture of methane (nearly 75 %), hydrogen sulphide, carbon dioxide and hydrogen. It is produced by the decomposition of animal wastes (cow dung) and plant wastes in the absence of oxygen. It is also commonly called as 'Gobar gas' since the starting material used is cow dung called as gobar.
Uses of biogas:
(i) It is used as fuel for cooking.
(ii) It is used to run motors and pump sets.
(iii) It is used to generate electricity.
Advantages of biogas:
(i) It burns without smoke and therefore causes less pollution.
(ii) An excellent way to get rid of organic wastes like bio-waste and sewage material.
(iii) Left over slurry is good manure rich in nitrogen and phosphorus
(iv) It is safe and convenient to use.
(v) It can reduce the amount of greenhouse gases emitted.

The various devices used for harvesting sun's energy are called solar energy devices.
Solar cells:
(i) Solar cells (Photovoltaic devices) is made up of silicon that converts sunlight directly into electricity.
(ii) Solar cell produces electricity without polluting the environment.
(iii) Since it uses no fuel other than sunlight, no harmful gases, no burning and no wastes are produced. These can be installed in remote and inaccessible areas (forests and hilly regions) where setting up of power plant is expensive
Uses of Solar cells:
(i) It can be used for street lighting, traffic signals, water pumping, battery charging system etc.
(ii) It is used in artificial satellites and space probes.
(iii) It provides radio and TV transmission to remote areas
(iv) It is used in calculators, electronic toys and watches.

a) Fossil fuels are natural fuel such as petroleum, coal and natural gas, formed in the geological past from the remains of living organisms.
b) Fossil fuels, found inside the earth’s crust, are formed by natural process, such as anaerobic decomposition of buried dead organisms.
c)The formation of fossil takes over millions of years.
d) Heat and pressure produced by the accumulating sediment layers gradually transform the remains of the organisms into hydrocarbons. e.g. Petroleum, Coal and Natural gas.

It is necessary to conserve or save coal and petroleum resources for the future use, which can be done by reducing their consumption
i) If electricity is saved, it will in turn reduce the use of coal.
ii) Using bicycle for covering short distances instead of using cars, scooters or motorcycles.
iii) Using pressure cooker can reduce the consumption of kerosene and LPG while cooking food. Solar cooker and solar heaters can be used wherever possible.
iv) Motor vehicles should be designed with fuel efficient engines to increase efficiency and also reduce air pollution