Which statement about pH and acid-base solutions is correct?
At temperatures above 298 K298\text{ K}298 K, the pH of pure water is less than 777.
At 298 K298\text{ K}298 K, a 2.0×10−3 mol dm−32.0 \times 10^{-3}\text{ mol dm}^{-3}2.0×10−3 mol dm−3 solution of the strong base barium hydroxide, Ba(OH)2\text{Ba(OH)}_2Ba(OH)2, has a pH of 11.3011.3011.30.
At 298 K298\text{ K}298 K, a 0.20 mol dm−30.20\text{ mol dm}^{-3}0.20 mol dm−3 solution of a weak acid with Ka=2.0×10−5 mol dm−3K_a = 2.0 \times 10^{-5}\text{ mol dm}^{-3}Ka=2.0×10−5 mol dm−3 has a pH of 0.700.700.70.
Diluting a strong acid solution by a factor of 100 increases its pH by 2.02.02.0 units, whereas diluting a weak acid solution by a factor of 100 also increases its pH by 2.02.02.0 units.
