The order of reactivity of the following alkyl bromides towards $S_N1$ reactions is:
$a$) $(CH_3)_2CHBr$
$b$) $CH_3CH_2Br$
$c$) $(CH_3)_3CBr$

Which reagent is used to convert an $Alkyl \ halide$ $(R-X)$ into an $Alkyl \ nitrite$ $(R-O-N=O)$?

At normal temperature,iodoform is:

Assertion $A:$ Hydrolysis of an alkyl chloride is a slow reaction but in the presence of $NaI$,the rate of the hydrolysis increases.
Reason $R:$ $I^{-}$ is a good nucleophile as well as a good leaving group.
In the light of the above statements,choose the correct answer from the options given below.

Consider the following bromides.
The correct order of $S_N1$ reactivity is

In the given reaction
$CH_3-CH(OTs)-CH_2-CH_2-CH(OTs)-CH_3$ $\xrightarrow[(ii) \ KOH]{(i) \ SH^{\ominus} (one \ equivalent)}$ $[X]$
$[X]$ will be :