The graph shows that the rate of reaction is slower and the reaction runs out of reactants sooner for the lower concentration of sulfuric acid. This indicates that zinc powder reacts more slowly with 0.05 mol/dm3 sulfuric acid than with 0.10 mol/dm3 sulfuric acid.
Figure 2 shows that zinc powder reacts more slowly with 0.05 mol/dm3 sulfuric acid than with 0.10 mol/dm3 sulfuric acid in two ways:
The slope of the line for the 0.05 mol/dm3 sulfuric acid is shallower than the slope of the line for the 0.10 mol/dm3 sulfuric acid. This means that the rate of reaction (the change in volume of gas per second) is slower for the lower concentration of sulfuric acid.
The line for the 0.05 mol/dm3 sulfuric acid reaches a plateau (levels off) sooner than the line for the 0.10 mol/dm3 sulfuric acid. This means that the reaction runs out of reactants (zinc powder or sulfuric acid) sooner at the lower concentration.