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

Which product is the major product in the photobromination of $2$-methylbutane?

The interaction that causes the most instability in the boat conformation of cyclohexane is .......

Which of the following yields both alkane and alkene?

Which one gives only one monosubstitution product on chlorination?

Given below are two statements:
Statement $I$ : The boiling point of three isomeric pentanes follows the order
$n$-pentane $>$ isopentane $>$ neopentane
Statement $II$ : When branching increases,the molecule attains a shape of sphere. This results in smaller surface area for contact,due to which the intermolecular forces between the spherical molecules are weak,thereby lowering the boiling point.
In the light of the above statements,choose the most appropriate answer from the options given below: