What is the number of molecules present in 16 g of O₂ at S.T.P.?
WBBSE
Class X
Physical Science
Behaviour of Gases
01 Mark
2025
3.01 × 10²³ molecules
Explanation
Molar mass of O₂ = 16 × 2 = 32 g/mol
Number of moles = \frac{\text{Mass}}{\text{Molar Mass}}
= \frac{16}{32}
= 0.5 mol
Number of molecules = 0.5 × 6.022 × 10²³ molecules
= 3.011 × 10²³ molecules ≈ 3.01 × 10²³ molecules
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