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NEET 2026
Exam
NEET
Year
2026
Subject
Chemistry
Chapter
Some Basic Concepts of Chemistry

NEET 2026 · Chemistry · Some Basic Concepts of Chemistry

The number of hydrogen atoms present in 5.4 g of urea is : (Given :...

The number of hydrogen atoms present in 5.45.4 g of urea is :
(Given : Molar mass of urea : 6060 g mol−1^{-1}, NA:6.022×1023N_A : 6.022 \times 10^{23} particles mol−1^{-1})

Options

  1. A1.084×10231.084 \times 10^{23}
  2. B1.084×10221.084 \times 10^{22}
  3. C2.168×10222.168 \times 10^{22}
  4. D2.168×10232.168 \times 10^{23}

Correct answer

D. 2.168×10232.168 \times 10^{23}

Step-by-step solution

The chemical formula of urea is NH2CONH2NH_2CONH_2.

Number of moles of urea =5.460=0.09= \dfrac{5.4}{60} = 0.09 mol.

One molecule of urea contains 44 hydrogen atoms.

Number of moles of hydrogen atoms =4×0.09=0.36= 4 \times 0.09 = 0.36 mol.

Total number of hydrogen atoms =0.36×NA=0.36×6.022×1023=2.16792×1023≈2.168×1023= 0.36 \times N_A = 0.36 \times 6.022 \times 10^{23} = 2.16792 \times 10^{23} \approx 2.168 \times 10^{23}.

Answer: 2.168×10232.168 \times 10^{23}
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