The following table shows the value of the ionisation constant of pure water at various temperatures and at a constant pressure.
| \(\text{Temperature (°C)}\) | \(0\) | \(25\) | \(50\) | \(75\) | \(100\) |
| \(K_W\) | \( 1.1 \times 10^{-15}\) | \( 1.0 \times 10^{-14}\) | \( 5.5 \times 10^{-14}\) | \( 2.0 \times 10^{-13}\) | \( 5.6 \times 10^{-13}\) |
Given this data, which one of the following statements about pure water is correct?
- The \(\ce{[OH–]}\) will decrease with increasing temperature.
- The \(\ce{[H3O+]}\) will increase with increasing temperature.
- Its pH will increase with increasing temperature.
- Its pH will always be exactly 7 at any temperature.
