$A$ point object on the principal axis at a distance $15\, cm$ in front of a concave mirror of radius of curvature $20\, cm$ has a velocity of $2\, mm/s$ perpendicular to the principal axis. The velocity of the image at that instant will be.......$mm/s$.

Boron forms covalent compounds due to:

The resistance of a wire is $R$. If the length of the wire is doubled by stretching,then the new resistance will be

$A$ hereditary disease which is never passed on from father to son is

Which gland is concerned with salt equilibrium in the body?