Which of the following pairs acts as a biofertilizer?

An engine giving a whistle is moving towards a stationary observer with a speed of $110\,m/s$. What will be the ratio of the frequency of the whistle heard when the engine is approaching and receding from the observer? (The speed of sound is $330\,m/s$.)

During the electrolysis of cryolite,aluminium and fluorine are formed in ........ molar ratio :

The number of atoms in $100 \ g$ of an $fcc$ crystal with density $d = 10 \ g/cm^3$ and cell edge length $a = 100 \ pm$ is:

The electric field for an electromagnetic wave in free space is $E = \hat{i} 30 \cos (kz - 5 \times 10^8 t)$,where the magnitude of $E$ is in $V/m$. The magnitude of the wave vector $k$ is (velocity of $EM$ wave in free space $= 3 \times 10^8 \ m/s$).

The ratio of specific heats of a gas is $\gamma$. The change in internal energy of one mole of the gas,when the volume changes from $V$ to $2 V$ at constant pressure $p$ is