Consider the following sequence of reactions :

The products $\left(\mathrm{A}\right)$ and $\left(\mathrm{B}\right)$ are, respectively :

Which of the following compounds react with aniline to give acetanilide.

What is the final product $\left(\mathrm{B}\right)$ of this sequence?

Which of the following is used to perform following transformation:

Which of the following reagents are involved in the following transformation ?