Science — AI-generated practice question

The pH of milk will decrease (become less than 6) as it turns into curd.

Reason: During the conversion of milk to curd, bacteria present in milk produce lactic acid (as seen in Table 2.3, sour milk/curd contains lactic acid). As lactic acid is formed, the concentration of H⁺ ions in the solution increases. Since higher H⁺ ion concentration corresponds to a lower pH value, the pH of the milk decreases, making curd more acidic than fresh milk.

Source: Chapter 2, Section 2.3 (Table 2.3); Chapter 2, Exercise Q.11

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• The key facts examiners expect: (1) pH decreases, (2) name the acid formed — lactic acid, (3) link acid formation → more H⁺ ions → lower pH. All three points together cover the 3 marks.
• Table 2.3 in Chapter 2 explicitly lists "Sour milk (Curd) → Lactic acid" — cite or reference this.
• Do not just say "it becomes acidic"; you must explain why using H⁺ ion concentration and the pH scale concept.