Pure Chemistry MCQ Revision

1) Which three salts are all prepared by titration?

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

3) Which equations below represent redox reactions?

1. H+ + OH− → H2O

2. MnO4− + 8H+ + 5e− → Mn2+ + 4H2O

3. Cl2 + 2Br −→ Br2 + 2Cl −

4) 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]

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

What could compound T be?

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

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

8) 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.

9) 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?

10) 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?

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

What are the reactants?

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

13) 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?

14) 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?

15) 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?

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

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

18) 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?

19) 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?

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

21) CH4, H2O and HCl are covalent compounds.

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

22) Which of these Group 1 elements reacts most violently with water?

23) 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?

24) 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?

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

Which ion is the catalyst in the reaction?

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

27) The structure of brass is shown below.

What is the purpose of adding zinc to copper?

28) 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?

29) 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?

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

31) Which statement is correct?

32) 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?

33) 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?

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

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

36) Which substances contain the same number of atoms?

37) 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?

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

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?