54) Salts of A (at.mass = 7), B (at. Mass = 27) and C (at. Mass = 64) were electrolysed under identical condition using the same quantity of electricity. It was found that when 2.1 g of A was deposited, the weights of B and C deposited were 2.7 g and 9.6 g. The valencies of A, B and C are respectively