$(11\mathrm{.}27)($a$)$ An oxygen$-16$ ion with a mass of $2\mathrm{.}66$x$10$ kg travels at $5\mathrm{.}0\backslash$times $10\backslash$deg m$/$s perpendicular to a $1\mathrm{.}20-$T magnetic field, which makes it move in a circular arc with a $0\mathrm{.}231-$m radius. What positive charge is on the ion? $($b$)$ What is the ratio of this charge to the charge of an electron