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NDA 2019 GAT · General Knowledge · Mole Concept and States of Matter · hard

Contains the greatest number of atoms? (Atomic masses: H = 1, He = 4, N = 14, O = 16)

Single correct option

Which of the following contains the greatest number of atoms? (Atomic masses: H = 1, He = 4, N = 14, O = 16)
  1. A. 1 g of hydrogen gas (H2)
  2. B. 1 g of helium gas
  3. C. 1 g of nitrogen gas (N2)
  4. D. 1 g of oxygen gas (O2)
Show answer and solution

Answer: (A) 1 g of hydrogen gas (H2)

Moles of atoms in 1 g are: H2 gives 1 mol of atoms, He gives 0.25 mol, N2 gives 2/28 = 0.071 mol and O2 gives 2/32 = 0.0625 mol. The lightest species gives the most particles per gram, and hydrogen is diatomic, doubling its atom count.
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Original question written in the NDA 2019 GAT pattern and checked twice for the correct answer. Not an official question paper. How we write and check questions · Corrections policy · Report a mistake