Question

If one mole of carbon atoms weighs 12 grams, what is the mass (in grams) of 1 atom of carbon?

NCERT Class IX
Sciences - Main Course Book

Chapter 3. Atoms and Molecules

Answer 1

1 mole of carbon atoms contains 6.023 × 10²³ atoms
so 6.023 × 10²³ atoms weighs 12 grams
so 1                 atom weighs  12/(6.023 × 10²³) grams = 2×10⁻²³ grams 

Answer 2

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Given: 1 mole of carbon weighs 12g

1 mole of carbon atoms = 6.022 X 10²³

Molecular mass of carbon atoms =

12g = an atom of carbon mass

Hence, mass of 1 carbon atom = 12 / 6.022 X 10²³ = 1.99 X 10-²³g