What is catenation?

How many chiral compounds are possible on monochlorination of $2$-methylbutane?

Arrange the following in decreasing order of their boiling points:
$(A)$ $2-$Methylbutane
$(B)$ $2,2-$Dimethylpropane
$(C)$ Pentane
$(D)$ Hexane

Which of the following has the highest knocking tendency in an internal combustion engine?

Arrange the following alkanes in order of their boiling points:
$A$. Pentane
$B$. $2-$Methylbutane
$C$. $2,2-$Dimethylpropane

Select the chain propagation steps in the free-radical chlorination of methane.
$(1) \, Cl_2 \to 2Cl^{\bullet}$
$(2) \, Cl^{\bullet} + CH_4 \to CH_3Cl + H^{\bullet}$
$(3) \, Cl^{\bullet} + CH_4 \to CH_3^{\bullet} + HCl$
$(4) \, H^{\bullet} + Cl_2 \to HCl + Cl^{\bullet}$
$(5) \, CH_3^{\bullet} + Cl_2 \to CH_3Cl + Cl^{\bullet}$