What is obtained when gypsum is heated at $300\,^oC$?

Consider the following reaction: $C_6H_5NO_2$ $\xrightarrow{Sn/HCl} X$ $\xrightarrow{C_6H_5COCl} Y + HCl$. What is $Y$?

$A$ regular polygon of $n$ sides has $170$ diagonals,then $n$ is equal to

Among the following,the molecule with the highest dipole moment is:

The plates of a parallel plate capacitor are charged up to $200 \ V$. $A$ dielectric slab of thickness $4 \ mm$ is inserted between its plates. Then,to maintain the same potential difference between the plates of the capacitor,the distance between the plates is increased by $3.2 \ mm$. The dielectric constant of the dielectric slab is:

Identify the incorrect pair from the following.