Calcium granules of mass 5.0 g were reacted with excess water in a flask on a balance. The mass of the reaction mixture was measured at regular time intervals; the results are in the table below. (Plot the graph on paper: mass of reaction mixture against time, labelled L.)

1. aUse your graph to determine the mass of reaction mixture after 5 minutes. [2]
2. bAn error was made when measuring one of the masses. Use your graph to determine the time when the error was made. [1]
3. cThe experiment was repeated with powdered calcium. Describe the graph that could be obtained (M). [2]
4. dWhy was the mass of the reaction mixture decreasing during the reaction? [1]

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