In an investigation of the rate of reaction between calcium carbonate and dilute hydrochloric acid, a student monitored the volume of carbon dioxide gas produced over time. The results are plotted on the graph below, and a dashed tangent line is drawn touching the curve at t=30 st = 30\text{ s}t=30 s.
Which of the following is the best estimate for the rate of reaction at t=30 st = 30\text{ s}t=30 s?
0.55 cm3 s−10.55\text{ cm}^3\text{ s}^{-1}0.55 cm3 s−1
0.70 cm3 s−10.70\text{ cm}^3\text{ s}^{-1}0.70 cm3 s−1
0.85 cm3 s−10.85\text{ cm}^3\text{ s}^{-1}0.85 cm3 s−1
1.10 cm3 s−11.10\text{ cm}^3\text{ s}^{-1}1.10 cm3 s−1
