The number of oxygen atoms bonded to one phosphorous atom in $P_4O_6$ is

$A$ uniform rod of mass $M$ and length $L$ is placed on a smooth horizontal surface. $A$ horizontal force $F$ is applied at one end of the rod perpendicular to its length. The acceleration of the centre of mass of the rod is:

Which of the following is a characteristic of $Pteridophytes$?

Water-containing cavities in vascular bundles are found in:

If the voltage between the terminals $A$ and $B$ is $17\,V$ and the Zener breakdown voltage is $9\,V$,then the potential across $R$ is....$V$

$A$ body is executing simple harmonic motion. At a displacement $x$ its potential energy is $E_1$ and at a displacement $y$ its potential energy is $E_2$. The potential energy $(E)$ at displacement $(x+y)$ is