How many structural isomers of amine are possible for the molecular formula $C_3H_9N$?

In amines,the hybridisation state of $N$ is

Consider the following sequence of reactions. Total number of $sp^{3}$ hybridised carbon atoms in the major product $C$ formed is . . . . . . .

In the given set of reactions,the $IUPAC$ name of product '$Y$' is:
$2-\text{Bromopropane}$ $\xrightarrow[\text{alc. / heat}]{AgCN} X$ $\xrightarrow{LiAlH_4} Y$

Which of the options correctly represents the basicity order for these compounds?

The correct order of decreasing basic strength of the following compounds is:
$(I)$ Aniline
$(II)$ $p$-Methoxyaniline
$(III)$ $p$-Nitroaniline
$(IV)$ $m$-Nitroaniline