In an $S_N2$ reaction on a chiral carbon atom,what is always produced?

Consider the following reactions:
$(a) \; (CH_3)_3CCH(OH)CH_3 \xrightarrow{conc. H_2SO_4} $
$(b) \; (CH_3)_2CHCH(Br)CH_3 \xrightarrow{alc. KOH} $
$(c) \; (CH_3)_2CHCH(Br)CH_3 \xrightarrow{(CH_3)_3CO^{-}K^{+}} $
$(d) \; (CH_3)_2C(OH)CH_2CHO \xrightarrow{\Delta} $
Which of these reaction$(s)$ will not produce Saytzeff product?

Ethyl acetate is obtained when methyl magnesium iodide reacts with

Which is the main organic product obtained by the reaction of $2,2,2-$trichloroethanol with calcium hydroxide?

Ethyl bromide gives ethylene when reacted with

Which of the following compounds has the highest boiling point?