Which one of the following acids is predominantly found in tomatoes?
- (a)Acetic acid
- (b)Tartaric acid
- (c)Oxalic acid
- (d)Lactic acid
Correct — C, Oxalic acid. In the standard natural-acids-and-sources table used in Indian school science, tomato is paired with oxalic acid, which is the acid this question is testing. The other three belong elsewhere — acetic acid to vinegar, tartaric acid to tamarind, and lactic acid to sour milk — so among the four choices oxalic acid is the one linked to tomatoes.
- (a)Acetic acid — Acetic acid is the acid present in vinegar, not the one associated with tomatoes.
- (b)Tartaric acid — Tartaric acid is found in tamarind and grapes, not in tomatoes.
- (d)Lactic acid — Lactic acid occurs in sour milk and curd (and forms in muscles during exercise), not in tomatoes.
Many fruits and vegetables get their sour taste from naturally occurring weak organic acids, and school science summarises them in a source-to-acid table. Tomato is listed with oxalic acid — the simplest dicarboxylic acid — which is also present in spinach.
This is a recall question best answered from the natural-acid table. Tomatoes in reality also contain citric and malic acids, but neither is offered here; of the four options, oxalic acid is the recognised textbook match, and the other three each point to a different, well-known source.
- In the natural-acids table, tomato is paired with oxalic acid.
- Acetic acid → vinegar; citric acid → citrus fruits; tartaric acid → tamarind and grapes; lactic acid → curd and sour milk.
- Oxalic acid also occurs in spinach and is the simplest dicarboxylic acid.
- These are all weak organic acids, unlike strong mineral acids such as HCl or H₂SO₄.
- Reaching for acetic acid (vinegar) out of habit.
- Forgetting that the textbook table pairs tomato specifically with oxalic acid.
Asked as 'which acid is found in [a given food]?' — a straight recall of the natural-acid-and-source table.
Consider the following statements: 1. Caffeine, a constituent of tea and coffee, is a diuretic. 2. Citric acid is used in soft drinks. 3. Ascorbic acid is essential for the formation of bones and teeth. 4. Citric acid is a good substitution for ascorbic acid in our nutrition. Which of the statements given above are correct?
- (a) 1 and 2 only
- (b) 1, 2 and 3 only
- (c) 3 and 4 only
- (d) 1, 2, 3 and 4
Answer(b) 1, 2 and 3 only — citric acid cannot substitute for ascorbic acid, so statement 4 is wrong.
Same theme — naming everyday organic acids and their food uses (citric, ascorbic), the same recall skill as matching oxalic acid to tomatoes.
The lactic acid that gets accumulated in the muscle cells during rigorous exercise causing muscle cramps is produced from
- (a) ATP
- (b) Pyruvate
- (c) Ethanol
- (d) Glucose
Answer(b) Pyruvate
Related — organic acids and their sources; lactic acid (a distractor here) is the acid of muscle cells and curd, distinct from the oxalic acid of tomatoes.
- practice — not a real PYQ
The sour taste of tamarind is mainly due to
- (a)acetic acid
- (b)tartaric acid
- (c)lactic acid
- (d)oxalic acid
Answer(b) tartaric acid — the acid associated with tamarind and grapes.
- practice — not a real PYQ
Which acid is present in vinegar?
- (a)citric acid
- (b)acetic acid
- (c)oxalic acid
- (d)lactic acid
Answer(b) acetic acid — dilute acetic acid is what vinegar is.