If a polygon of $n$ sides has $275$ diagonals,then $n$ is equal to

$A$ beam of electrons is moving with constant velocity in a region having electric and magnetic fields of strength $20 \; Vm^{-1}$ and $0.5 \; T$ at right angles to the direction of motion of the electrons. What is the velocity (in $m/s$) of the electrons?

The solubility of silver bromide in hypo solution is due to the formation of:

Rectified spirit is a mixture of

$A$ ray of light refracts from medium $1$ into a thin layer of medium $2$,crosses the layer,and is incident at the critical angle on the interface between medium $2$ and $3$ as shown in the figure. If the angle of incidence of the ray is $\theta$,the value of $\theta$ is

What are the products formed when an aqueous solution of magnesium bicarbonate is boiled?