Identify the reaction in which product is not correctly matched

Identify $A$ in the given chemical reaction.

The compound A (major product) is

Presence of which reagent will affect the reversibility of the following reaction, and change it to a irreversible reaction :

$\mathrm{C}{\mathrm{H}}_4+{\mathrm{I}}_2\underset{\mathrm{Reversible}}{\overset{\mathrm{hv}}{\rightleftharpoons }}{\mathrm{CH}}_3-\mathrm{I} + \mathrm{HI}$

The total number of monohalogenated organic products in the following (including stereoisomers) reaction is

$$\begin{gathered} \underset{(\mathrm{Simplest} \mathrm{optically} \\ \mathrm{active} \mathrm{alkene})}{\mathrm{A}} \underset{\left(\mathrm{ii}\right) {\mathrm{X}}_2/∆}{\overset{\left(\mathrm{i}\right) {\mathrm{H}}_2/\mathrm{Ni}/∆}{\to }} \end{gathered}$$

Which hydrogen in compound $\left(E\right)$ is easily replaceable during bromination reaction in presence of light ?

The nitrogen cycle is given below. Identify A and B in it.

Given below are two statements:

Statement-I : $2$ -methylbutane on oxidation with ${\mathrm{KMnO}}_4$ gives $2$ -methylbutan-$2$-ol.

Statement-II : $\mathrm{n}$ -alkanes can be easily oxidised to corresponding alcohol with ${\mathrm{KMnO}}_4$.

Choose the correct option :

What will be the major product in the following mononitration reaction?

The major product formed in the reaction given below will be :

Study the following illustration of nitrogen cycle and identify $\mathrm{A}, \mathrm{B}$ and $\mathrm{C}$ in it.