Electron was discovered by J. J. Thomson in 1897 when he was studying the properties of cathode ray.
The amu is a unit which means the mass per neutron, So the 74.55 means the mass per mole KCl. So the mole number of 2.330g KCl is 2.330/74.55=0.031 mol. The volume is 0.031/0.1250=0.248 L ≈ 250 mL. So the answer is a.
