Number of chiral carbon atoms in a sugar

This type of question, asked 2 times: 10 May 2023 S2, 19 May 2026 S1. All 2 questions below, oldest first.

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Question 1
10 May 2023 S2
62 $What is the number of chiral carbon atoms in threose?$
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Question 2
19 May 2026 S1
46 $What is the number of chiral carbon atoms in the open chain structure of glucose and fructose respectively?$
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