Alpha particles are the same as a helium nuclei (2 protons, 2 neutrons).
--> Charge of an alpha particle is 2x1.602x10^-19 C (use this value in calculations).
A lead(II) ion has a charge of +2 (hence, "II").
--> Charge of a lead(II) ion is 2x1.602x10^-19 C (use this value in calculations).