Two electric charges of $9 \mu C$ and $-3 \mu C$ are placed $0.16 \ m$ apart in air. There will be a point $P$ on the line joining the two charges and in between them where the electric potential is zero. The distance of $P$ from the $9 \mu C$ charge is (in $m$)

$A$ bar magnet of length $10 \, cm$ and having a pole strength equal to $10^{-3} \, Wb$ is kept in a magnetic field having magnetic induction $B$ equal to $4\pi \times 10^{-3} \, T$. It makes an angle of $30^{\circ}$ with the direction of the magnetic induction. The value of the torque acting on the magnet is:

If the $x$-coordinate of a point $P$ on the line joining the points $Q(2, 2, 1)$ and $R(5, 1, -2)$ is $4$,then the $z$-coordinate of $P$ is

They do not perform photosynthesis and primarily obtain nutrition through ingestion.

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

Which one of the following compounds gives aspirin on reacting with acetic anhydride in the presence of conc. $H_2SO_4$?