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Which substance is described as pure by a scientist? A - OCR Gateway - GCSE Chemistry: Combined Science - Question 9 - 2023 - Paper 3
Question 9
Which substance is described as pure by a scientist? A. A solution of sodium chloride B. An alloy C. Dilute sulfuric acid D. Distilled water Your answer
Worked Solution & Example Answer:Which substance is described as pure by a scientist? A - OCR Gateway - GCSE Chemistry: Combined Science - Question 9 - 2023 - Paper 3
Step 1
Identify the pure substance
Answer
Out of the options provided, distilled water is the only substance that can be described as pure. A scientist defines a pure substance as one that contains only one type of particle, and distilled water satisfies this criterion as it is free from impurities and other substances.
Step 2
Explain why the other options are not pure
Answer
- A solution of sodium chloride contains water and dissolved sodium chloride, making it a mixture.
- An alloy consists of two or more metals and is therefore also a mixture.
- Dilute sulfuric acid contains sulfuric acid and water, which means it is not a pure substance.