Question

Five moles of helium are mixed with two moles of hydrogen to form a mixture. Take molar mass of helium $M_1=4g$ and that of hydrogen $M_2=2g$. The equivalent molar mass of mixture is:

(as nearest integer)

Answer 1

Equivalent molar mass $=\frac{\sum n_i{m}_i}{\sum n_i}=\frac{\sum 5\times 4+2\times 2}{\sum 5+2}=\frac{24}{7}$.