Alkyl halides react with $Mg$ in dry ether to form

Identify the correct order of reactivity for the $E_2$ reaction with alcoholic $KOH$ for the following compounds:
$(i)$ $(CH_3)_3C-Cl$
(ii) $(CD_3)_3C-Cl$
(iii) $(CT_3)_3C-Cl$

What is an alcoholic solution of $KOH$ used for?

The product obtained on reaction of $C_2H_5Cl$ with hydrogen over palladium carbon is

Consider the $S_N1$ solvolysis of the following halides in aqueous formic acid:
$(I)$ $CH_3-CH(CH_3)-CH(Br)-CH_3$
$(II)$ $CH_3-C(CH_3)(Br)-CH_3$
$(III)$ $C_6H_5-CH(Br)-C_6H_5$
$(IV)$ $C_6H_5-CH(Br)-CH_3$
Which one of the following is the correct sequence of the halides given above in the decreasing order of their reactivity?

Which of the following reaction$(s)$ produce the Saytzeff product as a major product?