pH and indicators
3 marks · EasyClassify each solution by its pH.
A solution has a pH of 2. State whether it is strongly acidic, weakly acidic, neutral, weakly alkaline, or strongly alkaline.
A solution has a pH of 9. What type of solution is this according to the pH scale?
A solution has a pH of 7. What type of solution is this?
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(a) strongly acidic
(b) weakly alkaline
(c) neutral
Common mistakes: wrong assignment of acidity/alkalinity
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Marking points
B1 (a) · 1 mark · Correctly identifies pH 2 as strongly acidic
B1 (b) · 1 mark · Correctly identifies pH 9 as weakly alkaline
B1 (c) · 1 mark · Correctly identifies pH 7 as neutral
Worked solution
a. pH 2 is strongly acidic (on the pH scale, 0–3 is strongly acidic).
b. pH 9 is weakly alkaline (8–10 is weakly alkaline).
c. pH 7 is neutral.