In a hydroelectric power plant,more electrical power can be generated if water falls from a greater height because:

$A$ modern selenium solar cell can convert $25 \%$ of sunlight into electrical energy.

State any two impacts on the environment caused due to the increase in energy demand. Suggest any two steps to reduce energy consumption.

Enlist the energy changes taking place in a hydroelectric power station.

Vinod is a member of the school Eco-club. He knows about a school that is a zero-garbage zone. He expressed his willingness to his teachers to implement the same in his school. He decided to place different coloured dustbins for segregating biodegradable and non-biodegradable garbage as the first step. Now answer the following questions.
$(a)$ Why does Vinod want to segregate biodegradable and non-biodegradable waste?
$(b)$ What can Vinod do with the biodegradable waste?

Mention any four areas where solar cells are being used as a source of energy.