Science — AI-generated practice question

Lactic acid is listed as an acid because it produces H⁺ ions in solution, which is the property that defines an acid. Milk has a pH of 6, which is already slightly acidic (below 7).

When milk turns into curd, lactic acid is produced by bacterial action. This increases the concentration of H⁺ ions in the solution. Since higher H⁺ ion concentration means lower pH, the pH of curd will be less than 6 — making it more acidic than fresh milk.

Source: Chapter 2, Section 2.3 (Table 2.3 and pH scale discussion)

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• The key link is: acid → H⁺ ions → lower pH. Examiners expect you to connect lactic acid's acidic nature (H⁺ production) to the pH drop.
• Milk at pH 6 is already slightly acidic. Curd, having more acid, must have a lower pH than 6.
• Common mistake: saying curd is basic or neutral. Remember — pH < 7 = acidic, and more acid means pH goes further down, not up.
• This question is directly linked to Exercise Q.11 from Chapter 2.