The temperature difference required up to a water level difference of $1000 \,m$ for operating an Ocean Thermal Energy Conversion $(OTEC)$ system is: (in $^{\circ} C$)

Choose the correct statement.

Name two forms in which solar energy manifests itself in oceans.

Make a list of conventional and non-conventional sources of energy. Give a brief description of harnessing one non-conventional source of energy.

Mention three advantages of a solar cell.

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?