In a mass spectrometer an ion will have a smaller radius for

In a mass spectrometer, an ion will have a smaller radius for its circular path if: the magnetic field is weaker. its speed is greater. its mass is greater. its charge is greater.

Solution

The radius of the path of a charged particle in a mass spectrometer is given by

r = mv/qB

radius is inversely proportional to charge, therefore greater the charge the smaller the radius.

Answer is d.

its charge is greater