Please explain in detail why option (b) is not the answer, since I F charge is the charge required to deposit 1 equivalent of a substance.& 1F is also the charge on one mole of electrons, so option (b)should be the answer but according to answer key it is option (a)?


The number of electrons required to deposit 1 gm equivalent aluminium (at. wt. = 27) from a solution of aluminium chloride will be 
(A)  3           (B) 1                      (C)  4                    (D)  2