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CBSE Class 11 Chemistry MCQs – Avogadro’s Number and Calculations Online Test
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Class 11 Chemistry Chapter 1 MCQs – Avogadro’s Law and Mole Calculations Practice
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NCERT Class 11 Physical Chemistry Quiz – Avogadro’s Number and Calculations
📚 Introduction
Avogadro’s Number and Calculations is a fundamental topic under Chapter 1 – Some Basic Concepts of Chemistry in CBSE Class 11 Physical Chemistry. Understanding the concept of a mole, the relationship between mass, number of particles, and Avogadro’s constant (6.022×10²³) is crucial for mastering stoichiometry and quantitative analysis in Chemistry.
This online MCQ practice test is meticulously designed as per the NCERT Class 11 Chemistry syllabus, ensuring complete alignment with CBSE board exam standards. The quiz covers important areas like mole-to-particle conversions, molar mass relations, Avogadro’s hypothesis, and molecular calculations, helping students apply theory to real numerical problems.
Practicing these Avogadro’s Number and Calculations MCQs will strengthen your understanding of core Physical Chemistry principles, improve your problem-solving accuracy, and prepare you effectively for both CBSE exams and entrance tests like JEE and NEET.
🧩 Sample MCQs (with Answers & Explanations):
Q1. Avogadro’s number (Nₐ) represents the number of:
A. Atoms in 1 gram of a substance
B. Molecules in 1 mole of a substance
C. Electrons in one atom of hydrogen
D. Particles in 1 kg of a substance
✅ Answer: B
💡 Explanation: Avogadro’s number (6.022×10²³) defines the number of particles (atoms, molecules, or ions) present in one mole of any substance.
Q2. The number of atoms in 2 moles of oxygen gas (O₂) is:
A. 6.022×10²³ B. 1.204×10²⁴ C. 2.408×10²⁴ D. 3.011×10²³
✅ Answer: C
💡 Explanation: Each O₂ molecule has 2 atoms. Hence, atoms = 2 × (2 × 6.022×10²³) = 2.408×10²⁴ atoms.
Q3. How many molecules are there in 0.5 mol of a gas?
A. 3.011×10²³ B. 6.022×10²³ C. 1.505×10²³ D. 2.408×10²³
✅ Answer: A
💡 Explanation: 1 mole = 6.022×10²³ molecules, so 0.5 mol = 0.5 × 6.022×10²³ = 3.011×10²³ molecules.
Q4. The mass of 6.022×10²³ atoms of carbon (atomic mass = 12 u) is:
A. 6 g B. 12 g C. 24 g D. 3 g
✅ Answer: B
💡 Explanation: 6.022×10²³ atoms = 1 mole → 12 g of carbon.
Q5. The number of oxygen atoms in 4.5 moles of H₂O molecules is:
A. 2.711×10²⁴ B. 1.355×10²⁴ C. 9.033×10²³ D. 6.022×10²³
✅ Answer: A
💡 Explanation: Each H₂O molecule contains 1 oxygen atom → atoms = 4.5 × 6.022×10²³ = 2.711×10²⁴ atoms.