$n$-butane on heating with a catalytic mixture of $AlCl_3$ and $HCl$ gives:

When are the compounds called normal $(n-)$? Give an example.

What are $X$ and $Y$ respectively in the following reaction sequence?
Isopentane $\xrightarrow{KMnO_4} X$ $\xrightarrow{\text{dehydration}} \underset{\text{Major}}{Y}$

Which of the following is $NOT$ obtained when a mixture of bromoethane and $1$-bromopropane is treated with sodium metal in dry ether?

Aluminum carbide on reaction with $D_2 O$ gives $Al(OD)_3$ and '$X$'. What is '$X$'?

The angle strain in cyclobutane is