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Introduction of Fundamental Concepts of Chemistry

25 free MDCAT Chemistry MCQs on Introduction of Fundamental Concepts of Chemistry (PM&DC syllabus), each with the answer, an explanation and the textbook line it comes from. Tap to check, no sign-up.

MDCAT (Pakistan)ChemistryPre-medical (Grade 12)25 questions

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  1. Question 1

    Equal volumes of all gases at the same temperature and pressure contain equal numbers of particles. This is:

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    Answer: D) Avogadro's law

    Avogadro's law is why one mole of every gas has the same molar volume at STP. Source: Chemistry 11 KPK (taleem360.com), p. 16.

  2. Question 2

    Molarity of a solution is the:

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    Answer: A) Moles of solute per dm3 of solution

    Molarity (M) = moles of solute / volume of solution in dm3. Source: 11 Chemistry Book FBISE, p. 86.

  3. Question 3

    In producing medicines, stoichiometry mainly ensures the:

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    Answer: B) Accuracy of drug synthesis

    Exact amounts give the right dose of active ingredient without unreacted reactants or by-products. Source: 11 Chemistry Book FBISE, p. 91.

  4. Question 4

    Standard temperature and pressure (STP) means:

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    Answer: A) 273 K and 1 atm

    STP = 0 C (273 K) and 1 atmosphere (760 mm Hg). Source: Chemistry 11 KPK (taleem360.com), p. 16.

  5. Question 5

    What is the mass of 5 moles of water (H2O = 18 g/mol)?

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    Answer: B) 90 g

    Mass = moles x molar mass = 5 x 18 = 90 g. Source: Chemistry 11 KPK (taleem360.com), p. 10.

  6. Question 6

    The number of molecules in 22 g of CO2 (44 g/mol) is:

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    Answer: C) 3.011 x 10^23

    22/44 = 0.5 mol; 0.5 x 6.023 x 10^23 = 3.011 x 10^23 molecules. Source: Chemistry 11 KPK (taleem360.com), p. 10.

  7. Question 7

    How many moles are there in 60 g of NaOH (40 g/mol)?

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    Answer: A) 1.5 mol

    n = 60 / 40 = 1.5 mol. Source: Chemistry 11 KPK (taleem360.com), p. 10.

  8. Question 8

    What is the mass of 0.5 mol of CaCO3 (100 g/mol)?

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    Answer: B) 50 g

    Mass = 0.5 x 100 = 50 g. Source: Chemistry 11 KPK (taleem360.com), p. 10.

  9. Question 9

    How many formula units are present in 125 g of CuSO4.5H2O (250 g/mol)?

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    Answer: C) 3.011 x 10^23

    125/250 = 0.5 mol; 0.5 x 6.023 x 10^23 = 3.011 x 10^23 formula units. Source: Chemistry 11 KPK (taleem360.com), p. 10.

  10. Question 10

    In 2KClO3 -> 2KCl + 3O2, how many moles of O2 are formed from 10 mol of KClO3?

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    Answer: D) 15 mol

    Mole ratio O2 : KClO3 = 3 : 2, so 10 x 3/2 = 15 mol. Source: Chemistry 11 KPK (taleem360.com), p. 14.

  11. Question 11

    ZnCO3 -> ZnO + CO2. What mass of CO2 (44 g/mol) is produced by decomposing 8.8 mol of ZnCO3?

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    Answer: B) 387.2 g

    1 : 1 ratio gives 8.8 mol CO2 = 8.8 x 44 = 387.2 g. Source: Chemistry 11 KPK (taleem360.com), p. 15.

  12. Question 12

    In HCl + NaOH -> NaCl + H2O, how many moles of NaCl are produced from 15.5 g of HCl (36.5 g/mol)?

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    Answer: C) 0.425 mol

    15.5 / 36.5 = 0.425 mol HCl gives 0.425 mol NaCl (1 : 1). Source: Chemistry 11 KPK (taleem360.com), p. 10.

  13. Question 13

    S + O2 -> SO2. What volume of SO2 at STP is produced by burning 15 g of sulphur (32 g/mol)?

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    Answer: A) 10.5 dm3

    15/32 = 0.469 mol S gives 0.469 mol SO2; x 22.4 = 10.5 dm3. Source: Chemistry 11 KPK (taleem360.com), p. 17.

  14. Question 14

    H2 + Cl2 -> 2HCl. What volume of Cl2 is needed to form 10 dm3 of HCl (same conditions)?

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    Answer: B) 5 dm3

    Gas volumes are in the mole ratio: Cl2 : HCl = 1 : 2, so 10/2 = 5 dm3. Source: Chemistry 11 KPK (taleem360.com), p. 18.

  15. Question 15

    A 10.0 g alloy of aluminium and zinc is 36% aluminium by mass. The mass of zinc in it is:

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    Answer: D) 6.4 g

    Zinc = 100 - 36 = 64% of 10 g = 6.4 g. Source: Chemistry 11 KPK (taleem360.com), p. 20.

  16. Question 16

    2H2 + O2 -> 2H2O. If 4 mol of H2 react with 5 mol of O2, how much O2 is left unreacted?

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    Answer: A) 3 mol

    4 mol H2 need 2 mol O2, so 5 - 2 = 3 mol O2 remain (excess reagent). Source: Chemistry 11 KPK (taleem360.com), p. 21.

  17. Question 17

    When 1 mole of H2 and 1 mole of O2 are mixed for 2H2 + O2 -> 2H2O, the limiting reactant is:

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    Answer: B) H2

    1 mol O2 needs 2 mol H2, which is not available; H2 runs out first. Source: 11 Chemistry Book FBISE, p. 89.

  18. Question 18

    CO2 + H2O -> H2CO3. If 120 g of CO2 (44 g/mol) is dissolved in 80 g of water, the maximum mass of H2CO3 (62 g/mol) formed is about:

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    Answer: C) 169.1 g

    CO2: 2.73 mol, H2O: 4.44 mol; CO2 is limiting, so 2.73 x 62 = 169.1 g. Source: Chemistry 11 KPK (taleem360.com), p. 23.

  19. Question 19

    1.92 g of Mg (24 g/mol) is heated in excess oxygen: 2Mg + O2 -> 2MgO. The theoretical yield of MgO (40 g/mol) is:

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    Answer: D) 3.2 g

    0.08 mol Mg gives 0.08 mol MgO = 0.08 x 40 = 3.2 g. Source: Chemistry 11 KPK (taleem360.com), p. 24.

  20. Question 20

    40 g of urea (60 g/mol) is dissolved to make 500 cm3 of solution. Its molarity is about:

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    Answer: C) 1.33 M

    0.667 mol / 0.5 dm3 = 1.33 M. Source: 11 Chemistry Book FBISE, p. 86.

  21. Question 21

    250 cm3 of 0.1 M AgNO3 is added to excess NaCl. What mass of AgCl (143.5 g/mol) forms?

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    Answer: D) 3.59 g

    Moles AgNO3 = 0.1 x 0.25 = 0.025 = moles AgCl; x 143.5 = 3.59 g. Source: 11 Chemistry Book FBISE, p. 87.

  22. Question 22

    What volume of 0.5 M Na2SO4 reacts completely with 275 cm3 of 0.25 M BaCl2 (1 : 1)?

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    Answer: A) 137.5 cm3

    M1V1 = M2V2: V = 0.25 x 275 / 0.5 = 137.5 cm3. Source: 11 Chemistry Book FBISE, p. 87.

  23. Question 23

    Mg + 2HCl -> MgCl2 + H2. What volume of H2 at STP is collected from 100 g of Mg (24 g/mol)?

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    Answer: B) 93.3 dm3

    100/24 = 4.17 mol Mg gives 4.17 mol H2; x 22.4 = 93.3 dm3. Source: 11 Chemistry Book FBISE, p. 83.

  24. Question 24

    2Mg + O2 -> 2MgO. How many moles of O2 are needed to react with 4 moles of Mg?

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    Answer: C) 2 mol

    Mg : O2 = 2 : 1, so 4 mol Mg need 2 mol O2. Source: 11 Chemistry Book FBISE, p. 84.

  25. Question 25

    0.2 mol of Na2SO4 ionizes completely in water. The number of Na+ ions produced is about:

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    Answer: D) 2.4 x 10^23

    Each Na2SO4 gives 2 Na+: 0.4 mol x 6.023 x 10^23 = 2.4 x 10^23. Source: 11 Chemistry Book FBISE, p. 83.

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