Equal weights of ethane and hydrogen are mixed in an empty container at $25^{\circ} C$. The fraction of total pressure exerted by hydrogen is

$1 \ L$ of $N_2$ and $\frac{7}{8} \ L$ of $O_2$ gases are mixed at the same temperature and pressure. What is the relationship between their masses in the mixture?

The ratio of amounts of $H_2S$ needed to precipitate all the metal ions from $100 \ mL$ of $1 \ M$ $AgNO_3$ and $100 \ mL$ of $1 \ M$ $CuSO_4$ is

$A$ solution of $H_2SO_4$ is $31.4 \%$ $H_2SO_4$ by mass and has a density of $1.25 \ g \ mL^{-1}$. The molarity of the $H_2SO_4$ solution is . . . . . . $M$ (nearest integer) [Given molar mass of $H_2SO_4 = 98 \ g \ mol^{-1}$]

What is the percent atom economy if the formula weight of reactants and the formula weight of products are $45 \ u$ and $35 \ u$ respectively (in $\%$)?

When $5 \ L$ of a gas mixture of methane and propane is perfectly combusted at $0 \ ^\circ C$ and $1 \ atm$,$16 \ L$ of oxygen at the same temperature and pressure is consumed. The amount of heat released from this combustion in $kJ$ ($\Delta H_{comb.} (CH_4) = 890 \ kJ \ mol^{-1},$ $\Delta H_{comb.} (C_3H_8) = 2220 \ kJ \ mol^{-1}$) is