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

Five very long,straight wires are bound together to form a small cable. Currents carried by the wires are $I_1 = 20\ A, I_2 = -6\ A, I_3 = 12\ A, I_4 = -7\ A, I_5 = 18\ A$. The magnetic induction at a distance of $10\ cm$ from the cable is

The function of companion cells is:

The $r.m.s.$ value of an $AC$ of $50\,Hz$ is $10\,A$. The time taken by the alternating current to reach from zero to maximum value and the peak value of current will be:

The solubility of silver bromide in hypo solution is due to the formation of:

$A$ vessel contains hydrogen and nitrogen gases in the ratio $2:3$ by mass. If the temperature of the mixture of the gases is $30^{\circ} C$, then the ratio of the average kinetic energies per molecule of hydrogen and nitrogen gases is $($Molecular mass of hydrogen $=2$ and molecular mass of nitrogen $=28)$