$3 \ L$ mixture of $C_2H_6$ and $C_3H_8$ produces $8 \ L$ of $CO_2$ upon complete combustion. Find the volume of $C_2H_6$ in the mixture.

$10 \, L$ solution of urea contains $240 \, g$ urea. The active mass of urea will be

The hardness of a water sample (in terms of equivalents of $CaCO_3$) containing $10^{-3} \ M \ CaSO_4$ is ................... $ppm$ (Molecular mass of $CaSO_4 = 136 \ g \ mol^{-1}$)

In what ratio by mass carbon dioxide $(CO_2)$ and nitrogen $(N_2)$ should be mixed so that the partial pressure exerted by each gas is the same?

What will be the normality of a solution containing $4.9 \ g$ of $H_3PO_4$ dissolved in $500 \ mL$ water (in $N$)?

The conversion of oxygen to ozone occurs to the extent of $15\%$ only. The mass of ozone that can be prepared from $67.2 \ L$ of oxygen at $1 \ atm$ and $273 \ K$ will be ............ $g$.