Densities of air in chandigarh was found to be $1.156kgm^{-3}$. The temperature and pressure were recorded as $20^{\large\circ}C$ and $100.142\; KPa$. The average molecular mass of the air at that place in $g \;mol^{-1}$ is

Question

$(a)\;28.12\qquad(b)\;29.20\qquad(c)\;14.56\qquad(d)\;18.12$