Which one of the following is NOT correctly matched? (Substance) (Use)

1. A

   Silver bromide – artificial photosynthesis

   Silver bromide is used in photographic film and plates because it is light-sensitive, not in artificial photosynthesis. Pairing AgBr with artificial photosynthesis is therefore the mismatch. The question asks which pair is NOT correctly matched, so (a) is the official key.

2. B

   Silver iodide – artificial rain

   Silver iodide is used in cloud seeding for artificial rain. That pairing is standard and is not the mismatch.

3. C

   Lithium bicarbonate – treatment of rheumatism

   Lithium bicarbonate (and related lithium salts) appear in older medical lists for rheumatism/gout-type use. In this paper the pair is treated as correctly matched, so it is not the key.

4. D

   Milk of magnesia – antacid

   Milk of magnesia (aqueous magnesium hydroxide) is a common antacid and mild laxative. The pair is correctly matched.

Summary. Official key is (a). AgBr belongs to photography, not artificial photosynthesis. AgI is used for artificial rain; milk of magnesia is an antacid. The question is a ‘not correctly matched’ item.