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MCQ practice · SSC Chemistry Board questions · Chapter 6: Concept of Mole and Chemical Counting

Chattogram Board 2025

What is the mass in grams of one Al atom?

Think it through first, then pick an option.

  1. a 27
  2. b 4.482 × 10⁻²³
  3. c 1.66 × 10⁻²⁴
  4. d 3.16 × 10⁻²³
Answer and explanation

Correct answer: b 4.482 × 10⁻²³

One Al atom = 27/6.023 × 10²³ = 4.482 × 10⁻²³ g.

Why the other options are wrong

  • a 27: 27 g is one mole of Al; a single atom is 27/6.023 × 10²³ = 4.482 × 10⁻²³ g.
  • c 1.66 × 10⁻²⁴: 1.66 × 10⁻²⁴ g is one H atom; an Al atom is 4.482 × 10⁻²³ g.
  • d 3.16 × 10⁻²³: 3.16 × 10⁻²³ g is one F atom; an Al atom is 4.482 × 10⁻²³ g.