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ICSE Class 10 Chemistry Question 3 of 23

Solved 2024 Specimen Paper ICSE Class 10 Chemistry — Question 3

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3
Question

Question 1(iii)

The atomic masses of sulphur (S), oxygen (O), and helium (He) are approximately 32, 16, and 4 respectively.
Which of the following statements regarding the number of atoms in 32 g of sulphur, 16 g of oxygen, and 4 g of helium is correct?

P. 16 g of oxygen contains four times the number of atoms as 4 g of helium.

Q. 16 g of oxygen contains half the number of atoms as 32 g of sulphur.

  1. only P
  2. only Q
  3. both P and Q
  4. neither P nor Q
Answer

neither P nor Q

Reason —

Number of atoms = MassMolecular Mass\dfrac{\text{Mass}}{\text{Molecular Mass}} x NA

where NA is the Avogadro's number = 6.023 x 1023

Number of atoms in 32 g of sulphur (s) = 3232\dfrac{32}{32} x NA = NA

Number of atoms in 16 g of oxygen (O) = 1616\dfrac{16}{16} x NA = NA

Number of atoms in 4 g of helium (He) = 44\dfrac{4}{4} x NA = NA

Hence, all have same number of atoms which is = 6.023 x 1023