Which is the best method for the preparation of $N$-methylethanamide?

If aniline is treated with conc. $H_{2}SO_{4}$ and heated at $200^{\circ}C$,the product is

What is obtained when nitrobenzene is treated sequentially with $(i)$ $NH_4Cl / Zn$ dust and $(ii)$ $H_2SO_4 / Na_2Cr_2O_7$?

$R-NH_2 \to R-NH-CH_3$ (major product). The correct sequence of reagents is:

$A$ compound $(x)$ with molar mass $108 \ g \ mol^{-1}$ undergoes acetylation to give a product with molar mass $192 \ g \ mol^{-1}$. The number of amino groups in the compound $(x)$ is . . . . . .

Identify the strongest base from the following.