21)Geothermal energy is
molten lava on the surface of earth
The heat energy trapped in the certain region of earth’s crust is called geo thermal energy.
22)In a hydropower plant
Potential energy possessed by stored water is converted into electricity
The stored water behind the dam has a potential energy which charges into the kinetic energy of falling water. This kinetic energy is utilized to rotate the turbine to produce electricity.
23)Which is the ultimate source of energy?
Sun
Sun is the ultimate source of energy directly or indirectly, all the form of energy are desired from solar energy.
24)Which one of the following forms of energy leads to least environmental pollution in the process of its harnessing and utilisation?
Solar energy
Solar energy leads to least environmental pollution in the process of its harnessing and utilisation.
25)Ocean thermal energy is due to
temperature difference at different levels in the ocean
Energy of warm surface water used to vaporise the low boiling point liquid ammonia. This vapours at high pressure is used to strin the turbines to generate electricity. Deep ocean cold water again condenses the used vapour into liquid.
26)The major problem in harnessing nuclear energy is how to
dispose off spent fuel safely?
The waste product obtained from nuclear power plant is highly radioactive material and harmful for human beings and environment.
27)Which part of the solar cooker is responsible for green house effect?
Glass sheet
Glass lid of solar cooker trapped the heat energy inside the box.
28)A good fuel should possess
both high calorific value and moderate ignition temperature
29)The variety of coal which has the highest car-bon content
Anthracite
30)Which of the following is the ultimate source of energy?
Sun