One molecule of haemoglobin will combine with four molecules of oxygen. If $1.0 \mathrm{g}$ of haemoglobin combines with $1.53 \mathrm{mL}$ of ${\mathrm{O}}_2$ at body temperature $\left(37 °\mathrm{C}\right)$ and a pressure of $743 \mathrm{torr}$, what is the molar mass of haemoglobin?

If the answer is of type $\mathrm{y}\times {10}^3 \mathrm{g} {\mathrm{mol}}^{-1}$, report the value of $\mathrm{y}$ correct up to nearest integer.

A sample of natural gas is $85.2\%$ of methane (${\mathrm{CH}}_4$) and $14.8\%$ of ethane (${\mathrm{C}}_2{\mathrm{H}}_6$) by mass. What would be the density $\left(\mathrm{in} \mathrm{g}/\mathrm{L}\right)$ of this mixture at $18°\mathrm{C}$ and $748 \mathrm{mmHg}$?

Answer by rounding off up to two places of decimals.

The vapour pressure of water at $20°\mathrm{C}$ is $17.5 \mathrm{mm} \mathrm{Hg}$. Calculate the mass of water (in mg) per litre of air at $20°\mathrm{C}$ and $45\%$ relative humidity. $\left(\mathrm{R}=0.0821 \mathrm{atm} \mathrm{L} {\mathrm{mol}}^{-1} {\mathrm{K}}^{-1}\right)$

Answer correct up to two places of decimals.

After $11.2 \mathrm{g}$ of carbon reacts with oxygen originally occupying $21.2 \mathrm{litres}$ at $18°\mathrm{C}$ and $750 \mathrm{mm} \mathrm{of} \mathrm{Hg}$, the cooled gases are passed through $3 \mathrm{litres}$ of $2.50 \mathrm{M} \mathrm{NaOH}$ solution. Determine the concentration of $\mathrm{NaOH}$ remaining in the solution which is not converted to ${\mathrm{Na}}_2{\mathrm{CO}}_3.$

A volume of a gas weighing $8 \mathrm{g}$ was allowed to expand at a constant temperature until the pressure of the gas reduced to one-half of its former value. It was found that $500 \mathrm{mL}$ of the gas weighed $1.25 \mathrm{g}$. Determine the initial density of the gas in $\mathrm{g} {\mathrm{L}}^{-1}$.