The number of electron lost are 2
Explanation
Al +Mn^2+→ Al^3+ + Mn2
from equation above the oxidation of Al move from zero( 0) to positive three (3^+), while the oxidation of Mn move from oxidation state positive two( 2^+) to Zero. Since the oxidation for Mn is reduced from 2^+ to 0 the number of electron lost are 2
