An element $(X)$ forms compounds of the formula $XCl_3$,$X_2O_5$ and $Ca_3X_2$,but does not form $XCl_5$. Which of the following is the element $X$?

The dimensional formula of $\frac{1}{2} \mu_0 H^2$ (where $\mu_0 = \text{permeability of free space}$ and $H = \text{magnetic field intensity}$) is:

If the wavelength of an electromagnetic radiation is $2000 \ \mathring{A}$,what is its energy in ergs?

Two concentric hollow spherical shells have radii $r$ and $R$ $(R \gg r)$. $A$ charge $Q$ is distributed on them such that the surface charge densities are equal. The electric potential at the centre is

Which of the following reagents can form a hydrazone with alkanone?

$A$ person standing on a rotating platform has his hands lowered. He suddenly outstretches his arms. The angular momentum