Name the largest component of biogas.

What prevents us from making use of solar cell panels to meet all our domestic needs for electricity?

What is the role of a plane mirror and a glass sheet in a solar cooker?

Explain why obtaining energy from nuclear fusion reactions is preferable to obtaining energy from nuclear fission reactions. Give two reasons.

Write true or false for the following statement:
Glass cover in a solar heating device allows the short wavelength of ultraviolet radiations to enter the solar cooker.

The fraction of the sun's energy received on the earth is about: (in $\%$)