When glycerol is heated with $KHSO_4$,it gives:

What is the correct order of bond dissociation energy for the following $C-H$ bonds?
$I. \, CH_3-H$
$II. \, CH_3CH_2-H$
$III. \, CH_2=CH-CH_2-H$
$IV. \, C_6H_5-H$

The product $(x)$ is

Product $(C)$ is

Give the main product of the following reactions:
$(i)$ $1, 2-$dibromopropane + alcoholic $KOH$
$(ii)$ $1, 1, 2, 2-$tetrabromoethane + zinc powder in methanol

The product of the reaction is: