What is the product formed when chloroform reacts with zinc dust in the presence of water?

Which one of the following compounds is inactive towards $S_N1$ reaction?

The correct reactivity order for $E_2$ reaction with alcoholic $KOH$ will be:
$(i)$ $3-$chlorocyclohexene derivative (conjugated system)
(ii) $1-$chlorodecalin derivative (with double bond)
(iii) $1-$chlorodecalin (saturated)

Predict the order of reactivity of the following compounds in $S_N1$ reaction :
$(I)$ $CH_3-CH_2-CH(Br)-CH_3$
$(II)$ $(CH_3)_2CH-CH_2-Br$
$(III)$ $(CH_3)_3CBr$

The product $A$ of the following sequence of reactions is:
Ethylbenzene $\xrightarrow[(b) Cl_2, \Delta]{(a) Br_2, Fe}$ $\xrightarrow{(c) alc. KOH} 'A' \text{ (Major product)}$

Write a note on $S_{N}1$ reaction.