$A$ black metal foil is warmed by radiation from a small sphere at temperature $T$ and at a distance $d$. It is found that the power received by the foil is $P$. If both the temperature and the distance are doubled,the power received by the foil will be

$A$ coil of wire of radius $r$ has $600$ turns and a self-inductance of $108 \ mH$. The self-inductance of a coil with the same radius and $500$ turns is: (in $mH$)

Which of the following sets of variables gives a straight line with a negative slope when plotted? ($P =$ vapour pressure,$T =$ Temperature in $K$)

$A$ 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:

Which of the following alcohols reacts most rapidly with alkali metals?

$3.2$ moles of hydrogen iodide were heated in a sealed bulb at $444 \, ^oC$ until the equilibrium state was reached. Its degree of dissociation at this temperature was found to be $22 \%$. The number of moles of hydrogen iodide present at equilibrium are: