Science M.C.Q

Green house effect in a region occurs when heat radiation (infra-red radiation) are trapped in that region. When sunlight enters the solar cooker through a glass sheet, then the objects inside the solar cooker emit heat radiation (or infra-red radiation) due to their increased temperature. These radiations have long wavelengths and hence less energy. Therefore, they cannot pass through the glass sheet. Hence, interior of the solar cooker becomes warm due to the trapping of these radiation.

 It takes millions of Years of the formation of fossil fuels. So, they cannot be renewed in near future.

 This is because even spent fuel (nuclear waste) continues to emit harmful radiation.

Potential energy increases with increase in height.

Bio-gas is an excellent fuel as it contains up to 75% methane. It burns without smoke, leaves no residue like ash in wood, charcoal and coal burning. Its heating capacity is high. Bio-gas is also used for lighting.

Solar energy leads to least environmental pollution in the process of its harnessing and utilization.
In case of nuclear energy, the major concerns of pollution are while storage and disposal of spent fuels where there is always a risk of leakage of radiation.

In case of thermal energy, enormous amount of air pollution is produced.

Even in case of geothermal energy a little amount of pollution is produced.

A windmill works on kinetic energy of wind.

The Sun has been radiating an enormous amount of energy at the present rate for nearly 5 billion years and will continue radiating at that rate for about 5 billion years more. So, it can be taken as an inexhaustible source of energy.
Fossil fuels inside the earth are present in very limited amount.

Hydro and wind energy plants run with the help of air and do not cause any pollution.

It is very difficult to dispose waste from a nuclear power plant.

Large amount of fossil fuels are burnt every day in power stations to heat up water to produce steam which further runs the turbine to generate electricity.

The main ingredient of biogas is methane. Except option (c), all other options are correct.

Higher wind velocity will turn the turbine at higher speed. This will help in more power generation.

 Energy from warm surface is used to boil a volatile liquid. Vapours of this liquid are utilized to turn the turbine. Then vapours are channelized to deeper oceans so that they can cool down.

 When oxides of carbon, nitrogen and sulphur react with water vapours in the atmosphere, they form carbonic acid, nitric acid and sulphuric acid respectively. These acids come down to the earth with rain.

All forms of energy are derived from the sun.

 Water is stored behind dams. The stored water has potential energy. When water is released from the dam; Potential energy changes into kinetic energy. This kinetic energy is utilized to turn the turbine to generate electricity.