What is natural gas? How is it formed?

Energy from various sources is considered to have been derived from the sun. Do you agree? Justify your answer.

Why is hydrogen considered a cleaner fuel compared to $CNG$?

$(a)$ How does the construction of dams across rivers get linked with the production of greenhouse gases?
$(b)$ How do technological inputs improve the efficiency of biomass fuels?

"Electricity generated by the water stored in a dam can be considered to be another form of solar energy." Explain by describing the series of energy transformations in sequence taking place during the process.

Solar cooker takes more time as compared to the $LPG$ to boil potato or rice,yet Kunal uses solar cooker for such type of cooking:
$(a)$ Why does Kunal use solar cooker instead of $LPG$? Give reason for your answer.
$(b)$ Name the phenomenon which is responsible for obtaining high temperature in solar cooker?
$(c)$ What is the motivation behind using solar cooker?