Which elements are used to make a solar cell?

$A$ student constructed a box-type solar cooker. He found that it is not working efficiently. What could this be due to? Give any four possible mistakes in the construction and operation of the solar cooker. What maximum temperature can ordinarily be reached inside a solar cooker?

Where are solar cells used?

What is geothermal energy?

Choose the only renewable source of energy from the following:

What are hot spots inside the Earth's crust?