State the function of H2SO4 in each of the following reaction equations: (i) MgO + H2SO4 -> MgSO4 + H2O [2014/3] (ii) Cu + conc. H2SO4 -> CuSO4 + SO2 + 2H2O [2014/3]

The volume of 2 mol. per $\text{dm}^3$ HCl used ($\text{cm}^3$) is the independent variable, so it should be plotted on the x-axis.
The volume of $\text{H}_2$ evolved in $\text{cm}^3$ is the dependent variable, so it should be plotted on the y-axis.

For the x-axis (Volume of HCl), a scale of 1 cm representing 5 $\text{cm}^3$ or 10 $\text{cm}^3$ would be suitable to accommodate values from 5 to 45 $\text{cm}^3$.
For the y-axis (Volume of $\text{H}_2$), a scale of 1 cm representing 50 $\text{cm}^3$ or 100 $\text{cm}^3$ would be suitable to accommodate values from 120 to 600 $\text{cm}^3$.

Plot each pair of (Volume of HCl, Volume of $\text{H}_2$) from the table as a distinct point on the graph paper. For example, (5, 120), (15, 360), (25, 550), (35, 600), (45, 600).

Draw a smooth curve that passes through or as close as possible to the plotted points. The graph should initially show an increase in hydrogen volume with increasing acid volume, then level off once all the magnesium has reacted.

Label the x-axis as "Volume of 2 mol. per $\text{dm}^3$ HCl used ($\text{cm}^3$)" and the y-axis as "Volume of $\text{H}_2$ evolved ($\text{cm}^3$)". Give the graph a suitable title, such as "Graph of Volume of Hydrogen Liberated vs. Volume of Hydrochloric Acid".