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NEETChemistrySome Basic Concepts of Chemistry

What is the absolute mass of a single molecule of carbon dioxide ( CO ₂ )? (Given atomic masses: C = 12 u , O = 16 u ; N_ A = 6.022 10²³ mol ⁻¹ )

Options

  1. A2.65 10²⁵ g
  2. B7.31 10⁻²³ g
  3. C2.66 10⁻²³ g
  4. D3.72 10⁻²³ g

Correct answer

B. 7.31 10⁻²³ g

Step-by-step solution

The molar mass of CO ₂ is calculated as: Molar mass = 12 + (2 16) = 44 g mol ⁻¹ One mole of CO ₂ contains N_ A ( 6.022 10²³ ) molecules. Mass of one molecule = Molar mass N_ A Mass of one molecule = 44 g 6.022 10²³ Mass of one molecule 7.31 10⁻²³ g Multiplying the molar mass by N_ A gives 2.65 10²⁵ g , which is incorrect. Using the mass of a single oxygen atom ( 16 u ) instead of the whole molecule gives 2.66 10⁻²³ g . Using the molar volume ( 22.4 L ) instead of molar mass gives 3.72 10⁻²³ g . Answer: 7.31 10⁻²³ g

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