What is the major product of the following reaction?

Describe the following:
$(i)$ Acetylation
$(ii)$ Cannizzaro reaction
$(iii)$ Cross aldol condensation
$(iv)$ Decarboxylation

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.

Choose the correct option$(s)$ for the following reaction sequence. Consider $Q$,$R$ and $S$ as major products.

Hydrolysis of an ester gives a carboxylic acid which on Kolbe's electrolysis yields ethane. The ester is

Which of the following is the correct order of acidic strength?