For the best ecological balance,what percentage of the land mass of a country in the plains should be covered with forests (in $, \%$)?

Choose the correct option regarding the following statements:
$(1)$ $CO_2$ contribution in global warming is $60\%$.
$(2)$ Greenhouse effect occurs due to deforestation.
$(3)$ Due to the greenhouse effect,the present average temperature at the surface of the Earth is $15^oC$.
$(4)$ The amount of $DDT$ in small fish is $0.05\ ppm$.

List all the wastes that you generate at home,school,or during your trips to other places. Which could you very easily reduce? Which would be difficult or rather impossible to reduce?

Identify the incorrect statement.

$A$ greenhouse is primarily used to grow plants during the $..........$ season.

$FOAM$ stands for $........$