Mole Concept MCQs

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