A student places excess magnesium ribbon into $10\,\text{cm}^3$ of $0.5\,\text{mol dm}^{-3}$ sulfuric acid. The hydrogen gas formed is gathered, and its total volume is recorded at intervals of every $10$ seconds. The experiment is then carried out again, but this time $5\,\text{cm}^3$ of $0.5\,\text{mol dm}^{-3}$ sulfuric acid is mixed with $5\,\text{cm}^3$ of water, while the same mass of magnesium ribbon is used. Which line on the graph represents the findings of the second experiment?