Which one of the following organic acids is abundant in grapes, tamarind and banana?

The correct answer is D) Tartaric acid. It is the characteristic acid of grapes and the principal acid in tamarind pulp, which is why tamarind tastes so sharp. The fruit list follows standard textbook examples. In banana, malic and oxalic acids are more prominent, so treat banana as a textbook association rather than a precise chemistry fact.

Why the others are wrong:

• Acetic acid gives vinegar its sharpness. It is produced by fermentation of ethanol and is not a dominant acid in these fruits.
• Citric acid is the signature acid of citrus fruits such as lemon, orange and lime. It is linked to citrus, not to grapes or tamarind.
• Lactic acid is formed by bacterial fermentation of milk in curd and yoghurt, and it accumulates in muscles during anaerobic exertion. It has no place in these fruits.

Core concept: fruit acids are a recurring fixed-association topic in general science. For Mains, they connect to food processing, where natural acidulants such as tartaric and citric acid are used in preservation and flavouring.

Trap: aspirants pick citric acid because it is the most familiar acid. Remember that tartaric acid is the link to grapes, wine-making and tamarind.