Name two chemicals which are responsible for the thinning of the ozone layer.

Disposable plastic plates should not be used because

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?

Excessive exposure of humans to $UV$-rays results in:
$(i)$ Damage to immune system
$(ii)$ Damage to lungs
$(iii)$ Skin cancer
$(iv)$ Peptic ulcers

Why are non-biodegradable substances not broken down by microbes?

The most important compound which accounts for almost $80\%$ of the total depletion of the ozone layer is $.........$