Why are the solar cookers painted black?

Increasing demand for fossil fuels has caused harm to our environment. List its three ill-effects. Suggest three measures to reduce the consumption of fossil fuels.

Write the composition and source of $LPG$. Although liquefied gas is present in the cylinder,how does it appear as a gas in the burner?

How can solar energy be harnessed? Mention any two limitations in using solar energy. How are these limitations overcome?

Mention two disadvantages of using animal dung directly as a fuel.

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