What is the volume percentage of nitrogen gas in the atmosphere (in $\%$)?

Which of the following molecules react with haemoglobin of the blood to produce toxic effect?

Which of the following is used as a green solvent?

The presence of which of the following substances in flue gases is the best indicator of incomplete combustion of petrol or diesel in an automobile engine?

Provide the correct statement for the following: (Use $T$ for True and $F$ for False statements.) $(1)$ Plants obtain elements like carbon,hydrogen,and oxygen from air and water. $(2)$ Plants obtain elements like $N, P, K, Ca$ from the soil. $(3)$ Compound fertilizers contain nitrogen as ammonium nitrate,phosphorus as $PCl_3$,and potassium as $KO_2$. $(4)$ The use of $NPK$ fertilizers increases the production of crops and vegetables in the soil.

Which among the following statements is $NOT$ true according to principles of green chemistry?