The colour of hydrogen is

$A$ ray of light is incident on the hypotenuse of a right-angled prism after travelling parallel to the base inside the prism. If $\mu$ is the refractive index of the material of the prism,the maximum value of the base angle for which light is totally reflected from the hypotenuse is

If the best and the worst paper never appear together,then in how many ways can six examination papers be arranged?

If two solutions have the same osmolarity,they are said to be

$A$ current-carrying rectangular loop is placed near a straight infinitely long current-carrying wire as shown in the figure. The torque acting on the loop is

Inheritance of skin colour in human is an example of