21 st Century Chemistry Multiple Choice Question in Topic 3 Metals Unit 11 1. Consider the equation: 2Ca(s) + O 2 (g) 2CaO(s) Which of the following statements are correct? (1) Calcium and oxygen are reactants. (2) Calcium oxide is the product. (3) 2 moles of Ca react with 1 mole of oxygen to give 2 moles of calcium oxide. A (1) and (2) only B (1) and (3) only C (2) and (3) only D (1), (2) and (3) 2. Which of the following statements are correct? (1) One mole is the quantity of a substance that contains Avogadro number of particles. (2) One mole of zinc and one mole of iron have different masses. (3) The molar mass of a substance is the mass in grams of one mole of it. A (1) and (2) only B (1) and (3) only C (2) and (3) only D (1), (2) and (3) 3. The Avogadro's number (1) has the numerical value of 6.02 x 10 23. (2) varies with temperature and pressure. (3) is represented by the symbol L. A (1) only B (2) only C (1) and (3) only D (2) and (3) only 4. One mole of a substance is (1) the amount equal to the formula mass of the substance in gram. (2) the mass of a substance divided by its molecular mass. (3) the amount corresponding to its molar mass. A (1) and (2) only B (1) and (3) only C (2) and (3) only D (1), (2) and (3) 5. If 2 g of oxygen gas contains x molecules, how many molecules are present in 28 g of nitrogen gas? (Relative atomic masses: N = 14.0, O = 16.0) A x B 4x C 8x D 16x
6. If there are x molecules in 17.75 g of chlorine, how many molecules are present in 8 g of sulphur dioxide? (Relative atomic masses: O = 16.0, S = 32.0, Cl = 35.5) A x/4 B x/2 C x D 2x 7. The molecular formula of a gas is X 3. If the Avogadro's number is L mol -1, how many atoms are there in 48 g of X 3? (Relative atomic mass: X = 16.0) A 1/2 L B L C 2 L D 3 L 8. If 2 g of carbon monoxide gas contain x molecules, how many molecules are present in 1 g of hydrogen gas? (Relative atomic masses: H = 1.0, C = 12.0, O = 16.0) A 3.5 x B 5.5 x C 7 x D 11 x 9. Which of the following gases, each having a mass of 3.0 g, has the largest number of molecules at room temperature and pressure? (Relative atomic masses: H = 1.0, C = 12.0, N = 14.0, O = 16.0, F = 19.0, Ar = 40.0) A Oxygen B Hydrogen fluoride C Carbon dioxide D Argon 10. Which of the following gases contains the largest number of molecules at room temperature and pressure? (Relative atomic masses: H = 1.0, C = 12.0, N = 14.0, O = 16.0, F = 19.0, Cl = 35.5) A 4.0 g of hydrogen chloride B 38.0 g of fluorine C 18.0 g of ammonia D 58.0 g of carbon dioxide 11. The molecular formula of a gaseous element X is X 2. If the relative atomic mass of X is 14, what is the number of molecules in 112 g of the gas? (Avogadro's number = 6.02 x 10 23 ) A 4 B 8 C 4 x 6.02 x 10 23 D 8 x 6.02 x 10 23
12. The formula of ozone is O 3. If one mole of ozone contains y atoms, how many atoms will 2 moles of oxygen gas contain? A B C D y 2y 13. Which of the following contains the same number of atoms as 3.20 g of sulphur dioxide? (Relative atomic masses: H = 1, C = 12.0, N = 14.0, O = 16.0, F = 19.0, S = 32.0, Cl = 35.5) A 3.4 g of ammonia B 2.1 g of carbon monoxide C 0.3 g of hydrogen D 1.9 g of fluorine 14. 3 moles of magnesium chloride contains A 3 moles of molecules. B 6 moles of cations. C 6 moles of anions. D 9 moles of atoms. 15. Metal X forms an oxide. 32 g of this oxide contains 23.17 g of X. What is the mole ratio of X to oxygen in the oxide? (Relative atomic masses: O = 16.0, X = 56.0) A 1 : 1 B 1 : 2 C 2 : 3 D 3 : 4 16. An oxide of element X has the formula X 2 O 3. 14.28 g of this oxide contains 7.56 g of X. What is the relative atomic mass of X? (Relative atomic mass: O = 16.0) A 12.0 B 18.0 C 27.0 D 36.0 17. A mixture of iron(ii) nitrate and iron(ii) carbonate contain 2 moles of nitrate ions and 1.2 moles of iron(ii) ions. What is the number of moles of carbonate ions? A 0.2 B 0.7 C 1.4 D 1.7 18. What is the mass of oxygen in 24 g of nitric acid, HNO 3? (Relative atomic masses: H = 1.0, N = 14.0, O = 16.0) A 6.1 g B 8.0 g C 12.2 g D 18.3 g
19. What mass of water of crystallization is contained in 30 g of XSO 4 5H 2 O with molar mass of 250 g mol -1? (Relative atomic masses: H = 1.0, O = 16.0, S = 32.0) A 10.8 g B 18.0 g C 14.4 g D 21.6 g 20. The percentage by mass of water of crystallization in FeSO 4 7H 2 O is (Relative atomic masses: H = 1.0, O = 16.0, S = 32.0, Fe = 56.0) A 45.3 %. B 56.0 %. C 72.0 %. D 84.6 %. 21. What is the percentage by mass of X in K 2 X 2 O 7? (Relative atomic masses: O = 16.0, K = 39.0, X = 52.0) A 17.7 % B 25.1 % C 35.4 % D 40.8 % 22. Which of the following fertilizers contains the lowest percentage by mass of nitrogen? (Relative atomic masses: H = 1.0, N = 14.0, O = 16.0, Na = 23.0, S = 32.0, Cl = 35.5, K = 39.0) A Potassium nitrate B Sodium nitrate C Ammonium chloride D Ammonium sulphate 23. Assuming that the effectiveness of a nitrogen-containing fertilizer is proportional to its percentage by mass of nitrogen in the compound, which of the following compounds is the most effective fertilizer? Relative molecular mass A CO(NH 2 ) 2 60 B NH 4 NO 3 72 C NaNO 3 85 D (NH 4 ) 2 HPO 4 132 24. An ore sample contains 75% by mass of AlCl 3 while the other ingredients do not contain aluminium. The percentage by mass of aluminium in the sample is (Relative atomic masses: Al = 27.0, Cl = 35.5) A 15.17 %. B 25.17 %. C 35.17 %. D 45.17 %.
25. A silver coin, with a mass of 12.00 g was dissolved completely in concentrated nitric acid to give silver nitrate solution. When excess potassium chloride solution was added to the resulting solution, 14.35 g of a white precipitate were obtained. What is the percentage by mass of silver in the coin? (Relative atomic masses: Cl = 35.5, Ag = 108.0) A 45 % B 60 % C 75 % D 90 % 26. A salt KCl MgCl 2 nh 2 O contains 38.92% by mass of water of crystallization. What is the value of n? (Relative atomic masses: H = 1.0, O = 16.0, Mg = 24.0, K = 39.0, Cl = 35.5) A 5 B 6 C 7 D 18 27. The compound X 2 S contains 70.9 % by mass of X. What is the relative atomic mass of X? (Relative atomic mass: S = 32.0) A 17.5 B 23.0 C 39.0 D 80.0 28. XCl 3 contains 20.2 % by mass of the element X. What is the relative atomic mass of X? (Relative atomic mass: Cl = 35.5) A 26.96 B 45.44 C 53.88 D 136.24 29. An element forms an oxide X 2 O 5 which contains 35% by mass of oxygen. What is the relative atomic mass of the element X? (Relative atomic mass: O = 16.0) A 3.45 B 21.54 C 43.10 D 74.29 30. 2 moles of atoms of X combines with 16 g of oxygen to form an oxide. The empirical formula of this oxide is (Relative atomic mass: O = 16.0) A XO. B XO 2. C XO 3. D X 2 O. 31. A compound is formed when 71 g of chlorine is combined with 48 g of oxygen. What is the empirical formula of the compound? (Relative atomic masses: O = 16.0, Cl = 35.5) A ClO B ClO 2 C Cl 2 O D Cl 2 O 3
32. Heating 4.8 g of an element X give 9.6 g of its oxides. The empirical formula of the oxide is (Relative atomic masses: O = 16.0, X = 32.0) A XO. B X 2 O. C XO 2. D XO 3. 33. A compound contains carbon and hydrogen only. If the percentage by mass of hydrogen in the compound is 25 %, what is its empirical formula? (Relative atomic masses: H = 1.0, C = 12.0) A CH B CH 2 C CH 3 D CH 4 34. A compound contains 34.4 % nickel, 28.1 % carbon and 37.5 % oxygen by mass. Its empirical formula is (Relative atomic masses: C = 12, O = 16, Ni = 58.7) A NiCO. B Ni(CO) 4. C NiCO 3. D Ni(CO) 2. 35. What is the empirical formula of a compound with the following composition by mass? Na = 36.5 % S = 25.4 % O = 38.1 % (Relative atomic masses: O = 16.0, Na = 23.0, S = 32.0) A NaSO 3 B NaSO 4 C Na 2 SO 3 D Na 2 SO 4 36. Vitamin C contains 40.9 % of carbon, 4.6 % of hydrogen and 54.5 % of oxygen. The empirical formula of vitamin C is (Relative atomic masses: H= 1.0, C = 12.0, O = 16.0) A CH 2 O. B C 2 H 3 O 2. C C 3 H 4 O 3. D C 4 H 5 O 4. 37. 32.18 g of an oxide of metal M, when completely reduced by carbon, produced 4.95 g of carbon dioxide. What is the empirical formula of the oxide? (Relative atomic masses: C = 12.0, O = 16.0, M = 63.5) A MO B M 2 O C MO 2 D M 2 O 3 38. The empirical formula for a compound containing 18.2% of lithium, 71.2% of aluminium and 10.6% of hydrogen by mass is (Relative atomic masses: H = 1.0, Li = 7.0, Al = 27.0) A LiAlH 2. B LiAlH 4. C Li 2 AlH 5. D Li 3 AlH 5.
39. 24.42 g of a hydrated metal sulphate was heated to a constant mass. After cooling to room temperature, the residual, anhydrous metal sulphate weighted 11.92 g. How many moles of water of crystallization are there in one mole of the hydrated metal sulphate? (Relative formula masses: anhydrous metal sulphate = 120.0; water = 18.0) A 4 B 5 C 7 D 10 40. 4.68 g of a metal X combine with 2.16 g of oxygen to form an oxide in which the charge of the ion of X is +3. What is the relative atomic mass of X? (Relative atomic mass: O = 16.0 ) A 11.6 B 34.7 C 52.0 D 104 41. The formula of hydrated sodium carbonate crystals is Na2CO3 xh2o. When 66.9 g of the hydrated crystals are heated, 24.8 g of anhydrous sodium carbonate are produced. What is the value of x? (Relative atomic masses: H = 1.0, C = 12.0, O =16.0, Na = 23.0) A 3 B 5 C 7 D 10 42. What mass of iron is obtained when 0.60 mole of iron(iii) oxide are completely reduced by carbon monoxide? (Relative atomic masses: O = 16.0, Fe = 56.0) A 33.60 g B 43.23 g C 67.20 g D 96.10 g 43. The formula of hydrated iron(ii) sulphate is FeSO 4 xh 2 O. On strong heating, 14.07 g of the sulphate produces 6.37 g of water. What is the value of x? (Relative atomic masses: H = 1.0, O = 16.0, S = 32.0, Fe = 56.0) A 5 B 6 C 7 D 8 44. The following equation represents the reaction of an oxide of iron with carbon: Fe 3 O 4 (s) + 2C(s) 3Fe(s) + 2CO 2 (g) What mass of iron would be obtained if 80.99 g of the oxide was consumed in the reaction? (Relative atomic masses: O = 16.0, Fe = 56.0) A 19.53 g B 39.06 g C 58.65 g D 78.12 g
45. Aluminium can be produced from aluminium oxide by the following reaction: Al 2 O 3 (s) + 3Mg(s) 2Al(s) + 3MgO(g) What mass of aluminium oxide is required to produce 11.88 g of aluminium? (Relative atomic masses: O = 16.0, Al = 27.0) A 22.44 g B 33.66 g C 44.88 g D 67.32 g 46. Consider the following equation: 2NH 3 (g) + 3CuO(s) N 2 (g) + 3H 2 O(l) + 3Cu(s) What mass of ammonia would be required to give 0.45 mole of water in the reaction? (Relative atomic masses: H = 1.0, N = 14.0) A 5.10 g B 7.65 g C 11.45 g D 15.30 g 47. (NH 4 ) 2 X 2 O 7 decomposes on heating to give X 2 O 3, water and nitrogen. What mass of water is obtained when 277.2 g of (NH 4 ) 2 X 2 O 7 undergoes complete decomposition? (Relative atomic masses: H = 1.0, N = 14.0, O = 16.0, X = 52.0) A 19.8 g B 39.6 g C 79.2 g D 158.4 g 48. Consider the following equation: X 2 (g) + 3Y 2 (g) 2XY 3 (g) If 4 moles of X 2 (g) react with 6 moles of Y 2 (g), what is the number of moles of XY 3 (g) formed? A 2 B 4 C 8 D 10 49. The following equation represents the reaction of propane (C 3 H 8 ) with oxygen: C 3 H 8 (g) + 5O 2 (g) 3CO 2 (g) + 4H 2 O(l) What is the mass of carbon dioxide formed when 3 moles of propane react with 10 moles of oxygen? (Relative atomic masses: H = 1.0, C = 12.0, O = 16.0) A 132 g B 264 g C 308 g D 396 g 50. When 4 moles of hydrochloric acid react with 72 g of magnesium, the mass of hydrogen produced is (Relative atomic masses: H = 1.0, Mg = 24.0) A 2 g. B 3 g. C 4 g. D 6 g.