In humans,which disorder is caused due to the absence of one of the $X$ chromosomes,i.e.,$45$ with $XO$?

$A$ body of mass $2 \, kg$ slides down a curved track which is a quadrant of a circle of radius $1 \, m$. All the surfaces are frictionless. If the body starts from rest,its speed at the bottom of the track is ................. $m/s$.

The major product of the following reaction is

Explain why $BeH_{2}$ molecule has a zero dipole moment although the $Be-H$ bonds are polar.

Zero growth means:

If $f: R \rightarrow C$ is defined by $f(x)=e^{2 i x}$ for $x \in R$, then $f$ is (where $C$ denotes the set of all complex numbers)