$($a$)$ An oxygen$-16$ ion with a mass of $2\mathrm{.}66$x$10^-26$ kg travels at

$5\mathrm{.}00$x$10^6$ 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?

$($c$)$ Discuss why the ratio found in $($b$)$ should be an integer.