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Basic concepts

Written by Dr. Ayesha Nadeem (Chemistry)

Class 11 · Chemistry · 8 questions

Name: ____________________   Date: ____________

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

    • A 2
    • B 0.5
    • C 44
    • D 1

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

    • A 6.02 x 10^23
    • B 1.204 x 10^24
    • C 3.01 x 10^23
    • D 12 x 10^23 atoms

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

    • A CHO
    • B CH2O
    • C C2H4O2
    • D C3H6O3

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

    • A Is used up first
    • B Is in excess
    • C Is a catalyst
    • D Is a gas

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

    • A 1 dm3
    • B 24 dm3
    • C 22.4 dm3
    • D 11.2 dm3

  6. The mass of one mole of NaCl is: (Na = 23, Cl = 35.5)

    • A 35.5 g
    • B 23 g
    • C 58.5 g
    • D 81.5 g

  7. Percentage yield is:

    • A Theoretical yield / actual yield x 100
    • B Actual yield / theoretical yield x 100
    • C Actual yield x 100
    • D Theoretical yield only

  8. Avogadro's number is the number of particles in:

    • A One litre
    • B One gram
    • C One mole
    • D One kilogram

Answer key

1. D, 2. B, 3. B, 4. A, 5. C, 6. C, 7. B, 8. C

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

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

  3. Divide the subscripts by 6 to get CH2O.

  4. It runs out first and limits the amount of product.

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

  6. 23 + 35.5 = 58.5 g.

  7. It compares what you get with the maximum possible.

  8. One mole has 6.02 x 10^23 particles.