Which compound is formed when $CH_3OH$ reacts with $CH_3MgX$?

The decreasing order of boiling points of the following alkanes is:
$(a)$ Heptane
$(b)$ Butane
$(c)$ $2-$methylbutane
$(d)$ $2-$methylpropane
$(e)$ Hexane
Choose the correct answer from the options given below:

On exciting $Cl_2$ molecule by $UV$ light,we get

Knocking sound occurs in an engine when fuel:

For which of the following are only two isomeric monochloro derivatives possible?

What is the chief product obtained when $n$-butane is treated with bromine in the presence of light at $130^{\circ}C$?