The amine $\mathrm{A}$ when treated with nitrous acid gives a yellow oily substance. The amine $\mathrm{A}$ is ______.

During the acetylation of amines, _______.

An organic compound $\text{'}\mathrm{X}\text{'}$ having molecular formula ${\mathrm{C}}_4{\mathrm{H}}_{11}\mathrm{N}$ reacts with $\mathrm{p}-$toluenesulphonyl chloride to form a compound $\text{'}\mathrm{Y}\text{'}$ that is soluble in aqueous $\mathrm{KOH}$. Compound $\text{'}\mathrm{X}\text{'}$ is optically active and reacts with acetyl chloride to form compound $\text{'}\mathrm{Z}\text{'}$. Identify the compound $\text{'}\mathrm{Z}\text{'}$.

When aniline is treated with sodium nitrite and hydrochloric acid at $0°$$\mathrm{C}$, it gives ______.

In the Gattermann reaction, a diazonium group is replaced by $\mathrm{X}$ using $\mathrm{Y} ;$ $\mathrm{X}$ and $\mathrm{Y}$ are ______.

Which of the following is not formed by the Sandmeyer reaction?

Which will not go for diazotisation?

The reagent with which the following reaction is best accomplished is _____.

In the reaction,

the product $E$ is _______.