Which of the following is not a greenhouse gas?

Three waves of equal frequency having amplitudes $10 \mu m,$ $4 \mu m,$ and $7 \mu m$ arrive at a given point with a successive phase difference of $\frac{\pi}{2}.$ The amplitude of the resulting wave in $\mu m$ is given by

The displacement equations of sound waves produced by two sources are given by $y_1 = 5 \sin(400 \pi t)$ and $y_2 = 8 \sin(408 \pi t)$, where $t$ is time in seconds. If the waves are produced simultaneously, the number of beats produced per minute is

Two objects of masses $200 \text{ g}$ and $500 \text{ g}$ possess velocities $10 \hat{i} \text{ m/s}$ and $(3 \hat{i} + 5 \hat{j}) \text{ m/s}$ respectively. The velocity of their centre of mass in $\text{m/s}$ is:

What is the volume (in litres) of oxygen at $STP$ required for complete combustion of $32 \ g$ of $CH_4$ ? (Molecular weight of $CH_4$ is $16$ )

Which of the following is true in the case of an adiabatic process,where $\gamma = C_p / C_V$?