The graph shows the variation of potential difference (pd) with charge for a capacitor while it is charging - AQA - A-Level Physics - Question 25 - 2018 - Paper 2

The energy stored in a capacitor is given by the formula $E = \frac{1}{2} Q V$, where $E$ is the energy, $Q$ is the charge, and $V$ is the potential difference. The relationship in the graph implies that energy does not increase uniformly over time, as the charging process isn't linear. Thus, this statement is also incorrect.

The relationship between pd and charge determined from the graph suggests a linear characteristic, indicating that capacitance (defined as $C = \frac{Q}{V}$) remains constant. This statement aligns with the characteristics of a capacitor and is therefore correct.

The graph indicates that the potential difference increases with charge, rather than remaining constant. Hence, this statement is incorrect.