Waec Chemistry 2017 Past Questions and Answers

Question 51:

• WAEC 2017

Petroleum is a non-renewable source of energy because it

A. Is formed naturally
B. Is cheap
C. Can be recycled after use
D. Cannot be regenerated once used up

Question 52:

• WAEC 2017

(a)(i) What is an acid-base indicator?
(ii) Give one example of an acid-base indicator.

(b) State the property exhibited by nitrogen(IV) oxide in each of the following equations:,
(i) 4Cu + 2NO\(_2\) -> 4CuO + N\(_2\) (ii) H\(_2\)O + 2NO\(_2\) --> HNO\(_3\) + HNO\(_2\)

(c)(i) Define enthalpy of combustion..
(ii) State why the enthalpy of combustion is always negative.

(d)(i) Distinguish between a primary cell and a secondary cell.
(ii) Give an example of each of the cells stated in I (d)(i).
(e) Define the term mole.
(f) Calculate the amount of hydrochloric acid in 40.0 cm\(^3\) of 0.40 moldm\(^{-3}\) dilute HCl.
(g) Name two substances which can be used as electrodes during the electroylsis of acidified water.
(h) List two forces of attraction that can exist between covalent molecules.
(i) Name the products formed when butane undergoes incomplete combustion.
(j) Write the electron configuration of \(_{26}\)Fe\(^{3+}\)

Question 53:

• WAEC 2017

(a)(i) 1. State the periodic law.
2. What is meant by the term periodic property of elements?
(ii) List three properties of an element which show periodicity.
(iii) Explain briefly how each of the properties listed in (a)(i) in varies across the period.
(b) Defulle relative atomic mass.
(c)(i) What phenomenon is exhibited by an element Z which exist as \(^{35}_{17}Z\) and \(^{37}_{17}X\)
(ii) What accounts for the difference in the mass numbers of the element Z?
(iii) Calculate the relative atomic mass of Z if the percentage abundance of \(^{37}_{17}Z\) is 75%

(d)(i) State the method used for collecting each of the following gases: I. CO II. HCI III. H\(_2\)
(ii) Give a reason for your answer stated in (d)(i) I and II

Question 54:

• WAEC 2017

(a) Write the molecular formula of X.
(i) What type of reaction is represented by the equation?
(ii) Consider the following reaction equation: C\(_{12}H_2\) \(\to\) X + C\(_8\)H\(_{18}\)
(iii) Draw the structure of two isomers of X.
(iv) Name the isomers drawn in (a)(iii).
(v) Write a balanced equation for the reaction between X and hydrogen.

(b) Describe one test for fats.

(c) Sulphur (IV) oxide is converted to tetraoxosulphate (VI) acid according to the following equation: 2SO\(_{2(g)}\) + O\(_{2(g)}\) + 2H\(_2\)O\(_{(l)}\) \(\to\) 2H\(_2\)OSO\(_{4(aq)}\). If 1.5 moles of oxgen reacts with sulphur (IV) oxide, calculate the mass of tetraoxosulphate (VI) acid produced. [H = 1.0; O = 16.0; S = 32.0].

(d) Consider the following neutralization reaction:
CH\(_3\)COOH + NaOH \(\to\) CH\(_3\)COONa + H\(_2\)O; \(\bigtriangleup\)H\(_1\)
CH\(_3\)COOH + NH\(_4\)OH \(\to\) CH\(_3\)COONH\(_4\) + H\(_2\)O; \(\bigtriangleup\)H\(_2\)
NaOH + HCl \(\to\) NaCl + H\(_2\)O \(\bigtriangleup\)H\(_3\)
(i) Arrange the enthalphy changes for the reactions in order of increasing magnitude.
(ii) Explain briefly your order in (d)(i).

(e) Consider the following substances. Cu\(_{(s)}\), BeCl\(_2\), NaH\(_{(s)}\), HF\(_{(s)}\)and CCl\(_{4(l)}\). State the substance(s) which;
(i) can conduct electricity;
(ii) is/are soluble in water.

Question 55:

• WAEC 2017

(a)(i) Describe briefly the industrial preparation of ammonia.
(ii) Write a balanced equation for the reaction in (a)(i).
(iii) State one way of increasing the yield of ammonia in 4(a)(i).
(iv) State two uses of ammonia.

(b) Describe briefly, one chemical test for each of the following gases in the laboratory: (i) hydrogen; (ii) carbon (IV) oxide; (iii) oxygen.

(c)(i) State the composition of water gas.
(ii) List two uses of water gas.

(d) Describe briefly a simple experiment to determine the type of hardness in a sample of water.