Which of the following is not a Pteridophyte?

Two small drops of mercury,each of radius $R$,coalesce to form a single large drop. The ratio of the total surface energies before and after the change is

Which of the following is not a sex hormone?

$A$ point moves with uniform acceleration and $V_1, V_2$ and $V_3$ denote the average velocities in the three successive intervals of time $t_1, t_2$ and $t_3$. Which of the following relations is correct?

The chemical entities present in the thermosphere of the atmosphere are: