$A$ sample of gasoline contains $81\%$ iso-octane and $19\%$ $n$-heptane. Its octane number will be

Predict the major product for the following reaction:
$Methylcyclohexane \xrightarrow{Br_2, h\nu} \text{Major Product}$

Presence of which reagent will affect the reversibility of the following reaction,and change it to an irreversible reaction:
$CH_4 + I_2 \xrightarrow{hv} CH_3-I + HI$

The relative reactivity of $1^o H$,$2^o H$,and $3^o H$ in bromination reaction has been found to be $1 : 82 : 1600$ respectively. In the reaction $CH_3-CH(CH_3)-CH_3 \text{ (excess)} + Br_2$ $\xrightarrow{hv} CH_3-C(Br)(CH_3)-CH_3 \text{ (A)} + CH_3-CH(CH_3)-CH_2-Br \text{ (B)}$,the percentage yields of the products $(A)$ and $(B)$ are expected to be:

$Ph-CH=NO_2H$ $\xrightarrow[{3 \ days}]{{isomerises}}$ $\mathop {(x)}\limits_{(50-50\%)}$,Isomer $(x)$ is

Which of the following conditions will give the maximum yield of $C_2H_5Cl$?