When the pollen tube enters the ovule through the integuments,the process is known as?

For $100\%$ modulation $(AM)$,the useful part of the total power radiated is

The potential energy of a body of mass $m$ is given by $U = ax + by$,where $x$ and $y$ are the position coordinates of the particle. The acceleration of the particle is

Consider the following statements $A$ and $B$ and identify the correct answer:
$A$. When a person walks on a rough surface, the direction of the frictional force exerted by the surface on the person is in the direction of his motion.
$B$. When a cycle is in motion, the force of friction exerted by the ground on the front wheel is in the backward direction.

Arrange the carbanions,$(CH_3)_3\bar{C}$,$\bar{C}Cl_3$,$(CH_3)_2\bar{C}H$,$C_6H_5\bar{C}H_2$ in order of their decreasing stability.

Which one of the following statements is not correct?