Let $R$ be a relation on a set $A$ such that $R = R^{-1}$,then $R$ is

The polar equation $\cos \theta + 7 \sin \theta = \frac{1}{r}$ represents a

Under which one of the following conditions do real gases approach the ideal gas behaviour?

Some inert gas is added at constant volume to the following reaction at equilibrium:
$NH_4HS_{(s)} \rightleftharpoons NH_{3(g)} + H_2S_{(g)}$
Predict the effect of adding the inert gas.

Two photons of energy $2.5 \ eV$ and $3.5 \ eV$ fall on a metal surface of work function $1.5 \ eV$. The ratio of the maximum velocities of the photoelectrons emitted from the metal surface is

How many types of sporophylls are found in Pteridophytes?