Moving Charges Questions

Ionized hydrogen atoms and $\alpha$ -particles with same momenta enter perpendicular to a constant magnetic field, $B$. The ratio of their radii of their paths $r_H:r_{\alpha }$ will be:

A cylindrical conductor of radius $R$ is carrying a constant current. The plot of the magnitude of the magnetic field $B$ with the distance $d$ from the centre of the conductor, is correctly represented by the figure: