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Basic concepts

5 Class 11 Chemistry questions with answers and explanations.

Printable worksheet with answer key

All questions with answers
  1. How many moles are in 44 g of CO2? (C = 12, O = 16)

    • 1 2
    • 2 0.5
    • 3 44
    • 4 1
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    Correct answer: 1

    Molar mass = 44 g/mol, so 44 g is 1 mole.

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  2. The number of molecules in 2 moles of a gas is:

    • 1 6.02 x 10^23
    • 2 1.204 x 10^24
    • 3 3.01 x 10^23
    • 4 12 x 10^23 atoms
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    Correct answer: 1.204 x 10^24

    2 x 6.02 x 10^23 = 1.204 x 10^24.

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  3. The empirical formula of a compound with the molecular formula C6H12O6 is:

    • 1 CHO
    • 2 CH2O
    • 3 C2H4O2
    • 4 C3H6O3
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    Correct answer: CH2O

    Divide the subscripts by 6 to get CH2O.

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  4. The limiting reagent in a reaction is the one that:

    • 1 Is used up first
    • 2 Is in excess
    • 3 Is a catalyst
    • 4 Is a gas
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    Correct answer: Is used up first

    It runs out first and limits the amount of product.

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  5. What volume does 1 mole of any gas occupy at STP?

    • 1 1 dm3
    • 2 24 dm3
    • 3 22.4 dm3
    • 4 11.2 dm3
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    Correct answer: 22.4 dm3

    At STP one mole of an ideal gas occupies 22.4 dm3.

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