The main aim of the 'Earth Summit' organized in Brazil was:

"Good ozone" is found in the

In which layer of the atmosphere is the ozone layer located?

Which of the following statement$(s)$ is/are correct?
$(i)$ The Montreal Protocol was signed in $1987$ and became effective in $1989$.
$(ii)$ 'Good' ozone is found in the troposphere.
$(iii)$ Ozone is formed by the action of $UV$ rays on molecular oxygen and degrades into molecular oxygen.
$(iv)$ $CFCs$ are responsible for the imbalance between the production and degradation of ozone.
$(v)$ $DNA$ and proteins of living organisms absorb $UV$ rays.

$CFCs$ are responsible for:

Ultraviolet radiation from sunlight acts on $O_2$ to produce . . . . . . .