Mole Concept and Stoichiometry Quiz - ICSE Class 10 Chemistry
Free practice quiz: Mole Concept and Stoichiometry (ICSE Class 10 Chemistry). 47 multiple-choice questions with answers and explanations. Play online, no sign-up needed.
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A compound has an empirical formula CH2O. If its molar mass is 180 g/mol, what is its molecular formula?
- C3H6O3
- C6H12O6
- CH2O
- C2H4O2
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Answer: B. C6H12O6
The empirical formula mass of CH2O is 12 + 2(1) + 16 = 30 g/mol. The ratio of the molar mass to the empirical formula mass is 180 / 30 = 6. Therefore, the molecular formula is (CH2O)6, which is C6H12O6.
When 2 moles of hydrogen gas react with 1 mole of oxygen gas, how many moles of water are produced according to the equation 2H2 + O2 -> 2H2O?
- 1 mole
- 2 moles
- 3 moles
- 4 moles
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Answer: B. 2 moles
The balanced equation shows a 2:1 mole ratio between hydrogen and oxygen, producing 2 moles of water. Since we have 2 moles of H2 and 1 mole of O2, both reactants are consumed completely according to the stoichiometry. Therefore, 2 moles of water are produced.
What is the number of oxygen molecules in 11.2 L of oxygen gas at STP?
- 6.022 x 10^23
- 1.2044 x 10^24
- 3.011 x 10^23
- 1.5055 x 10^23
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Answer: C. 3.011 x 10^23
At STP, 1 mole of any gas occupies 22.4 L. 11.2 L of oxygen gas is equal to 11.2 L / 22.4 L/mol = 0.5 moles of oxygen gas (O2). Number of molecules = moles * Avogadro's number = 0.5 mol * 6.022 x 10^23 molecules/mol = 3.011 x 10^23 molecules.
What is the number of moles in 64 g of O2? (Molar mass of O2 = 32 g/mol)
- 1 mole
- 2 moles
- 3 moles
- 4 moles
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Answer: B. 2 moles
Moles of O2 = Mass of O2 / Molar mass of O2 = 64 g / 32 g/mol = 2 moles.
If 10 g of a substance has 0.1 moles, what is its molar mass?
- 10 g/mol
- 100 g/mol
- 0.1 g/mol
- 1 g/mol
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Answer: B. 100 g/mol
Molar mass = Mass / Moles = 10 g / 0.1 mol = 100 g/mol.