Pure Chemistry MCQ Revision

1) 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.

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

3) CH4, H2O and HCl are covalent compounds.

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

4) A paper chromatography experiment was carried out to determine the inks present in a mixture, and the results shown below were obtained.

Which statement about the results is incorrect?

5) 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?

6) 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?

7) Which element does not form a stable ion with the same electronic configuration as neon?

8) The following chemicals are available in the laboratory.

1. aqueous bromine
2. Universal Indicator solution
3. magnesium powder
4. sodium carbonate

Which of these chemicals can be used to distinguish between propene and propanoic acid?

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

10) When a 10 cm3 sample of a gaseous hydrocarbon was completely burnt in 35 cm3 of oxygen, the total volume of the products formed was 50 cm3.

Which equation represents the combustion of the hydrocarbon?

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

12) The structure of brass is shown below.

What is the purpose of adding zinc to copper?

13) 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?

14) 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?

15) 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?

16) Which three salts are all prepared by titration?

17) Which substances contain the same number of atoms?

18) In which chemical reaction does the named product have a higher relative molecular mass than the reactant?

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

What could compound T be?

20) The diagram shows the apparatus used to separate hexane (boiling point, 70 oC) and heptane (boiling point, 98 oC).

21) When crude oil is fractionally distilled, which list best describes the mixture of compounds collected at the bottom of the fractionating column?

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

23) Which equations below represent redox reactions?

1. H+ + OH− → H2O

2. MnO4− + 8H+ + 5e− → Mn2+ + 4H2O

3. Cl2 + 2Br −→ Br2 + 2Cl −

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

25) 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?

26) Calcium nitrate crystals contain water of crystallisation. Its formula may be written as Ca(NO3)2●nH2O.

When a 7.00 g sample of hydrated calcium nitrate is heated to remove all water, 4.90 g of anhydrous calcium nitrate remains after heating.

What is the value of n?

27) Heavy water is made up of 2 deuterium( Hydrogen atoms with mass number 2)  atoms and 1 oxygen atom.

Which properties are true about heavy water?

1 Its boiling point is higher than 100 °C.

2. It reacts with sodium to form sodium hydroxide and hydrogen gas.

3 It can act as a solvent for sodium chloride.

28) 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?

29) The structure of a compound associated with the smell of raspberries is shown below.

30) 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?

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

32) 50.0 cm3 of 0.10 mol/dm3 silver nitrate, AgNO3, is added to 150.0 cm3 of 0.05 mol/dm3 of sodium iodide, NaI, in a beaker.

After the reaction, solid silver iodide is present in the beaker. What else is present in the mixture?

33) 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?

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

35) 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?

36) 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?

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

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

Which ion is the catalyst in the reaction?

39) Which statement is correct?

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

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