$A+2B+3C \to AB_2C_3$ Reaction of $60\;g$ of $A, 6.0 \times 10^{23}$ atomic mass of A and C are $60$ and $80$ amu, respectively , the atomic mass of B is (Avogadro no $=6 \times 10^{23}$):

Question

$\begin{array}{1 1} 70\;amu \\ 60\;amu \\ 50\;amu \\ 40\;amu \end{array} $