The work function of a metal is $4.2 \ eV$. Its threshold wavelength will be ............ $\mathring{A}$.

In the circuit shown in the figure,the $AC$ source gives a voltage $V = 20 \cos(2000t)$. Neglecting source resistance,the voltmeter and ammeter readings will be:

If $C_p$ and $C_v$ denote the specific heats of nitrogen per unit mass at constant pressure and constant volume respectively,then

When bauxite powder is mixed with coke and reacted with nitrogen at $2075 \ K$,carbon monoxide and $X$ are formed. What is the gas formed when $X$ is reacted with water?

The electron in a hydrogen atom makes a transition from an excited state to the ground state. Which of the following statements is true?

The species having tetrahedral shape is