Science — AI-generated practice question

Importance of pH in Everyday Life

1. pH and our digestive system:
Our stomach produces hydrochloric acid (HCl) which helps in digestion. During indigestion, excess acid is produced causing pain. Antacids like Milk of Magnesia (magnesium hydroxide), which are mild bases, neutralise the excess acid and provide relief.

2. pH and tooth decay:
Bacteria in the mouth break down sugar to produce acids. When pH of the mouth falls below 5.5, the tooth enamel (calcium hydroxyapatite) gets corroded, causing tooth decay. Toothpastes are basic in nature and help neutralise this acid, preventing decay.

3. pH and acid rain/aquatic life:
Normal rain water has pH of about 5.6. When dissolved pollutants lower the pH below 5.6, it is called acid rain. When this flows into rivers, the pH of river water decreases, making survival of aquatic organisms difficult, as they can survive only in a narrow pH range.

(Bonus: Our body functions within a pH range of 7.0 to 7.8; bee stings inject acid and are relieved by applying a mild base like baking soda.)

Source: Chapter 2, Section 2.3.1

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• The question asks for any THREE examples, so choose three and write each as a clear, labelled point.
• Examiners expect: the example name → the pH-related problem → how pH knowledge helps solve/explain it.
• Common mistakes: writing only what happens without linking it to pH; forgetting the remedy or consequence.
• The 5-mark allocation means ~3 marks for three examples (1 mark each) + 1–2 marks for introduction/accuracy, so keep each point substantive but concise.
• "Acid rain," "digestion/antacids," and "tooth decay" are the three explicitly detailed examples in section 2.3.1—always prefer these.