Photo AI
The pH of unpolluted rainwater is about 6.0 - HSC - SSCE Chemistry - Question 5 - 2001 - Paper 1
Question 5
The pH of unpolluted rainwater is about 6.0. Which substance contributes most to this? (A) CO₂ (B) N₂ (C) NO₂ (D) O₃
Worked Solution & Example Answer:The pH of unpolluted rainwater is about 6.0 - HSC - SSCE Chemistry - Question 5 - 2001 - Paper 1
Step 1
Identify the substance that contributes most to the pH of unpolluted rainwater
Answer
Unpolluted rainwater has a pH of around 6.0, which indicates that it is slightly acidic. This acidity mainly comes from dissolved carbon dioxide (CO₂), which reacts with water to form carbonic acid (H₂CO₃). Therefore, among the options provided, the substance that contributes most to this is CO₂.