Which among the following metals is involved in the preparation of a Grignard reagent?

What will be the reduction products of the following reactions:
$CHCl_3 \xrightarrow[Zn/HCl \text{ (alc.)}]{+2H}$
$CHCl_3 \xrightarrow[Zn/HCl \text{ (aq.)}]{+4H}$
$CHCl_3 \xrightarrow[Zn/H_2O]{+6H}$

In the reaction,$2 A + \text{dry silver oxide} \xrightarrow{\Delta} \text{ether} + 2 \operatorname{Ag} X$,$A$ is a/an

$n-$propyl bromide on treating with alcoholic $KOH$ produces

The reactivity of alkyl bromides towards iodide ion in dry acetone decreases in the order:
$I. CH_3CH_2Br$
$II. CH_3-CH(CH_3)-Br$
$III. CH_3-C(CH_3)_2-Br$
$IV. CH_3Br$

The arrangement of the following compounds in the increasing order of their boiling points is:
$i$. bromomethane
$ii$. bromoform
$iii$. chloromethane
$iv$. dibromomethane