Mole ConceptPractice Questions & MCQs
Practice Mole Concept questions from Atoms and Molecules (Class 9 Science) - important MCQs with answers and step-by-step solutions. Solve the sample questions below, then practice the full set free on the RankByte app.
Mole ConceptQuiz - Solve & Score
Q1. Two moles of water contain how many molecules?
- A.1.2044 x 10^24
- B.6.022 x 10^23
- C.3.011 x 10^23
- D.2
Answer: A. 1.2044 x 10^24
NCERT fact (chemistry, chapter 'Atomic Foundations of Matter'): Convert mass -> moles -> particles in one chain: n = m / M (moles), then N = n * 6.022e23 (particles), where M is the molar mass found by summing atomic masses; substituting the data of the stem => N reduces to the listed value; hence the answer = 1.2044 x 10^24. Why option A fits - Correct. Distractor analysis: option B) '6.022 x 10^23' is wrong because That is one mole; two moles is twice that; option C) '3.011 x 10^23' is wrong because Two moles is 2 x Avogadro, not half of it. Final answer - A) 1.2044 x 10^24.
Q2. Which statement about a mole is correct?
- A.the mass of one mole differs from substance to substance but the particle number is fixed
- B.the mass of one mole is the same for all substances
- C.one mole always weighs 1 g
- D.the particle number changes with the substance
Answer: A. the mass of one mole differs from substance to substance but the particle number is fixed
Q3. How many molecules are in 32 g of a compound whose molar mass is 16 g/mol?
- A.12.044 x 10^23 molecules
- B.85.022 x 10^23 molecules
- C.2 x 10^23 molecules
- D.192.704 x 10^23 molecules
Answer: A. 12.044 x 10^23 molecules
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