The mean of the numbers obtained on throwing a die having $1$ on three faces,$2$ on two faces,and $5$ on one face is

$A$ ball is dropped from a height of $20 \ m$ above the surface of water in a lake. The refractive index of water is $4/3$. $A$ fish inside the lake, in the line of fall of the ball, is looking at the ball. At an instant, when the ball is $12.8 \ m$ above the water surface, the fish sees the speed of the ball as ........ $m/s$ $[g = 10 \ m/s^2.]$

$A$ thin flexible wire of length $L$ is connected to two adjacent fixed points and carries a current $I$ in the clockwise direction as shown. When the system is placed in a uniform magnetic field of strength $B$ directed into the plane of the paper,the wire takes the shape of a circle. The tension in the wire after acquiring the circular shape is

Which one of the following equations represents the Freundlich adsorption isotherm?

The ratio of the de-Broglie wavelength of an $\alpha$-particle to that of a proton,when both are subjected to the same magnetic field such that the radii of their paths are equal,assuming the magnetic field induction vector $\overrightarrow{B}$ is perpendicular to the velocity vectors of both particles,is:

When a proton is accelerated through $1\,V,$ then its kinetic energy will be........$eV$.