Which part of the solar cooker is responsible for the greenhouse effect?

The energy liberated by burning $1 \,g$ of charcoal is approximately: (in $,kJ$)

In a hydro power plant,

There are about $50$ teachers in a school and most of them come to school by their own cars. Many of the teachers come from the same place but everyone prefers to come to school by his/her own car.
Answer the following questions based on the above information:
$(a)$ Do you think that their practice of commuting to school is environmental-friendly? Give one suggestion. Justify your answer.
$(b)$ In what other two ways can we become environmental-friendly?

Mention any two differences between the two common designs of solar cooker.

Explain how hydroelectricity is produced.