Pure Chemistry MCQ Revision

1) 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?

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

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

4) 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?

5) 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?

6) 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?

7) 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.

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

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

10) Which equations below represent redox reactions?

1. H+ + OH− → H2O

2. MnO4− + 8H+ + 5e− → Mn2+ + 4H2O

3. Cl2 + 2Br −→ Br2 + 2Cl −

11) CH4, H2O and HCl are covalent compounds.

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

12) 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.

13) Which substances contain the same number of atoms?

14) An unknown solid Q has the following properties.

•When aqueous sodium hydroxide is added until in excess to the solution, no visible reaction is observed.

• When dilute acid is added to Q, effervescence of a colourless gas is observed.

• Q dissolves in water to form a colourless solution.

• Q is stable to heat.

What is Q likely to be?

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

What are the reactants?

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

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

18) 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?

19) A student has five reagents.

• dilute hydrochloric acid

• dilute sulfuric acid

• dilute nitric acid

• solid calcium carbonate

• solid copper(II) carbonate

How many soluble salts can be prepared?

20) 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?

21) The structure of brass is shown below.

What is the purpose of adding zinc to copper?

22) 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?

23) 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?

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

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

Which ion is the catalyst in the reaction?

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

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

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

29) 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?

30) 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?

31) Which statement is correct?

32) 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?

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

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

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

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

36) In which equation does the metal oxide act as an acidic oxide?

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

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

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

40) 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?