If volume charge density is $\rho$,then what will be the charge on $\Delta V$ volume?

$A$ square plate of side $a$ is placed in the $xy$-plane with its center at the origin. If the surface charge density of the square plate is given by $\sigma = xy$,then the total charge on the plate will be:

$A$ solid sphere of radius $R_1$ and volume charge density $\rho = \frac{\rho_0}{r}$ is enclosed by a hollow sphere of radius $R_2$ with negative surface charge density $\sigma$, such that the total charge in the system is zero. $\rho_0$ is a positive constant and $r$ is the distance from the centre of the sphere. The ratio $R_2/R_1$ is

The electric flux is $\phi = \alpha \sigma + \beta \lambda$,where $\lambda$ and $\sigma$ are linear and surface charge density,respectively. The ratio $\left(\frac{\alpha}{\beta}\right)$ represents:

$A$ non-uniformly shaped conductor is charged. Then,at its sharpest point:

Explain linear charge density,surface charge density,and volume charge density for uniform charge distribution.