Pure Chemistry MCQ Revision

1) Which of the following statements about a homologous series is correct?

2) An element T forms an ion, T2+, which has an electronic arrangement 2.8.8.

Which statement(s) concerning T is/are correct?

I T is an alkali metal.

II T forms a basic oxide with oxygen.

III T is in Period 4 of the Periodic Table.

3) An unknown substance X starts melting at –180 °C and finishes melting at –160 °C. What is substance X likely to be?

4) Elements X and Y combine to form an ionic compound. Atoms of X have more protons than atoms of Y.

Atoms of Y have more valence electrons than atoms of X. Which statement is correct?

5) Three elements W, X, Y, and Z have consecutive, increasing proton (atomic) numbers. Element Y exists as a colourless, monatomic gas at room temperature.

Which will be the chemical formula of a compound formed between W and chlorine?

6) Which statement explains why sodium chloride, NaCl, has a lower melting point than magnesium oxide, MgO?

7) Which compound has the lowest percentage by mass of nitrogen?

8) When excess aluminium oxide, Al2O3 was added to a portion of dilute sodium hydroxide. Which of the following correctly describes the pH change and the explanation?

9) Which statement does not explain why the speed of the reaction between zinc and dilute sulfuric acid increases when the acid is warmed?

10) A solution of a lithium halide and a halogen are mixed. A reaction occurs and the mixture darkens in colour.

What are the reactants?

11) CH4, H2O and HCl are covalent compounds.

Which atoms in these compounds do not use all their outer shell electrons in bonding?

12) Which property of elements increases from left to right of Period 3 of the Periodic Table?

13) Water is formed when oxygen combines with hydrogen. What mass of oxygen combines with 6 g of hydrogen?

14) The partial structure of a polymer is shown below.

15) Hydrogen gas reacts with chlorine gas to form hydrogen chloride gas.

H2(g) + Cl2(g) → 2HCl(g)

What is the final volume of the gas mixture when 20 dm3 of hydrogen is reacted with 30 dm3 of chlorine gas at 100 C?

16) Francium, Fr, is an element in the same group of the Periodic Table as lithium, sodium and potassium. Which statement about francium is likely to be correct?

17) The flowchart shows some reactions of a compound T.

What could compound T be?

18) Which equations below represent redox reactions?

1. H+ + OH− → H2O

2. MnO4− + 8H+ + 5e− → Mn2+ + 4H2O

3. Cl2 + 2Br −→ Br2 + 2Cl −

19) Which of the following hydrocarbons would produce the sootiest flame when burnt in air?

20) Which three salts are all prepared by titration?

21) An impure sample of calcium carbonate with a mass of 1.70 g was reacted with excess hydrochloric acid and 360 cm3 of carbon dioxide was collected at room temperature and pressure. What is the percentage purity of the calcium carbonate?

22) A student investigated the diffusion of ammonia gas, NH3, and hydrogen chloride gas, HCl. Two sets of apparatus were set up as shown below at room temperature and pressure.

The damp red litmus paper in apparatus 1 changed colour after 30 seconds. How long does it take for the damp blue litmus paper to change colour in apparatus 2?

23) Lead(IV) chloride has a melting point of -15 °C and boiling point of 50 °C.

Which type of structure do you expect lead(IV) chloride to have?

24) Which statement is correct?

25) A reaction takes place in two stages in the presence of a catalyst:

Which ion is the catalyst in the reaction?

26) A warship had its hull plated in copper to protect its wooden hull from rotting. However, after 2 years at sea, it was found that the iron parts of the warship in contact with the copper plates were more corroded than normal. What is the best explanation for this observation?

27) Which statement about the electrolysis of molten magnesium chloride is incorrect?

28) On adding 50 g of impure limestone, CaCO3 (Mr = 100), to excess hydrochloric acid, 6.0 dm3 of CO2 was evolved at room temperature and pressure.

What is the percentage purity of the limestone?

29) Oxygen was prepared and collected using the apparatus as shown in the diagram below.

The first tube of gas collected was discarded as it was contaminated. Which contaminant was in the gas?

30) Elements X, Y and Z are in the same period of the Periodic Table. Gaseous X exists as diatomic molecules.

Oxides of Y react with both acid and alkali.

Oxides of Z dissolve in water to form solution with pH > 7.

In which order do the elements appear in the Periodic Table?

31) Which diagram best represents the structure of calcium oxide?

32) Which of the following is the process by which a polyester is broken down into its monomers?

33) During an electrolysis experiment, the same amount of charge deposited 32.5 g of zinc and 10.2 g of vanadium.

What was the charge on the vanadium ion?

34) How many of the following processes will lead to an increase in greenhouse gas emissions?

35) Which of the following statements about isotopes is correct?

36) The structure of brass is shown below.

What is the purpose of adding zinc to copper?

37) The energy level diagram of a reaction is shown below.

Which arrow represents the overall enthalpy change of the reverse reaction?

38) Aqueous hydrogen peroxide decomposes to form water and oxygen gas. Two experiments were carried out to measure the rate of production of oxygen from aqueous hydrogen peroxide.

39) Ammonia and excess carbon dioxide can react to form urea and water in a reaction.

2NH3 + CO2 → CON2H4 + H2O

The percentage yield of this reaction is 80 %.

What is the mass of ammonia required for this reaction to obtain 60.0 g of urea?

[Mr: NH3, 17; CO2, 44; CON2H4, 60; H2O, 18]

40) Which one of the following could be used to distinguish aqueous solutions of sodium chloride and sodium iodide?