44 given the balanced ionic equation:
3pb2+ + 2cr ==> 3pb + 2cr3+
what is the number of moles of electrons gained by 3.0 moles of lead ions?
(1) 5.0 mol (3) 3.0 mol
(2) 2.0 mol (4) 6.0mol
i know that the answer is 4 i just need an explanation of how

To solve this redox equation, we divide the equation into two parts: the oxidation and the reduction part. The reduction part is 3 Pb 2+ = 3 Pb while the oxidation part is 2 Cr = 2 Cr3+. We balance the charges. 3 Pb 2+ + 6e- = 2 Pb and 2 Cr = 2 Cr 3+  + 6e-. Adding the two equations, the 6 e- just cancels out. Hence for 3 moles of lead ions, there are 6 moles of electrons gained.

Iwould you figure it out but you don't have a picture or in your question as to what the physical property you're looking for is