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NEETChemistrySome Basic Concepts of Chemistry

Which of the following samples contains the highest number of atoms?

Options

  1. A16 g of CH ₄
  2. B22.4 L of CO ₂ at STP
  3. C18 u of H ₂ O
  4. D2 moles of O ₂

Correct answer

A. 16 g of CH ₄

Step-by-step solution

The number of atoms in each sample is calculated as follows: 1) 16 g of CH ₄ = 16 16 mol = 1 mol of CH ₄ . Since each CH ₄ molecule contains 5 atoms (1 carbon and 4 hydrogen), total atoms = 5 N_A . 2) 22.4 L of CO ₂ at STP = 1 mol of CO ₂ . Each CO ₂ molecule contains 3 atoms, total atoms = 3 N_A . 3) 18 u of H ₂ O corresponds to the mass of exactly 1 molecule of H ₂ O , which contains 3 atoms (not moles). 4) 2 moles of O ₂ contains 2 N_A molecules. Each O ₂ molecule contains 2 atoms, total atoms = 4 N_A . The high

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