The number of methoxy groups in a compound can be determined by treating it with

When compound $X$ is oxidised by acidified potassium dichromate,compound $Y$ is formed. Compound $Y$ on reduction with $LiAlH_4$ gives $X$. $X$ and $Y$ respectively are:

The major product expected from the following reaction is:
$2-(\text{carbamoyl})-3-(\text{hydroxymethyl})-6-(\text{hydroxy})\text{benzoic acid} \xrightarrow{HCl_{(g)} / CCl_4} ?$

The product $(A)$ obtained is:

The general formula for monocarboxylic acids is

Give plausible explanation for each of the following:
$(i)$ Cyclohexanone forms cyanohydrin in good yield but $2,2,6-$trimethylcyclohexanone does not.
$(ii)$ There are two $-NH_2$ groups in semicarbazide. However,only one is involved in the formation of semicarbazones.
$(iii)$ During the preparation of esters from a carboxylic acid and an alcohol in the presence of an acid catalyst,the water or the ester should be removed as soon as it is formed.