MCQ practice · SSC Chemistry Board questions · Chapter 6: Concept of Mole and Chemical Counting
How many atoms are there in one molecule of sodium lauryl sulphate?
Think it through first, then pick an option.
- a 39
- b 41
- c 43
- d 45
Answer and explanation
Correct answer: c 43
C₁₂H₂₅SO₄Na: 12 C + 25 H + 1 S + 4 O + 1 Na = 43 atoms.
Why the other options are wrong
- a 39: 39 misses 4 atoms; C₁₂H₂₅SO₄Na has 12 + 25 + 1 + 4 + 1 = 43.
- b 41: 41 misses 2 atoms; 12 + 25 + 1 + 4 + 1 = 43.
- d 45: 45 has 2 too many; the right number is 43.
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