Waec Chemistry 2013 Past Questions and Answers

Question 46:

• WAEC 2013

Which of the following materials is classified as a non-biodegradable pollutant?

A. Animal hide
B. Paper
C. Plastic
D. Wood

Question 47:

• WAEC 2013

Bronze is a mixture of

A. Cu and Mg
B. Cu and Sn
C. Cu and Zn
D. Cu and Pb

Question 48:

• WAEC 2013

Which of the following statements about thermoplastic material is correct? They

A. Do not melt on heating
B. Harden on heating
C. Decompose on heating
D. Soften and melt on heating

Question 49:

• WAEC 2013

(a)(i) What is the common name given to the group VII elements?
(ii) Name the hydrides of the first two elements in group VII.
(iii) State three chemical properties of group VII elements.
(b) Copy and complete the following table:

Particles	Numberof Neutrons	Numberof electrons	Numberof prontons	Mass Number
W\(^{2+}\)	12			24
X\(^{2+}\)			8	16
Y		13		27
Z	12	11

(c)(i) Define each of the followinc processes: I. nuclear fission; II. nuclear fusion.
(ii) Give one use of each process in (c)(i).
(d)(i) List three types of radiation that are produced during radioactivity.
(ii) Arrange the radiations listed in
(d)(i) in order of increasing: I. penetrating power; II. ionizing power.

Question 50:

• WAEC 2013

(a)(i) Define each of the following terms: I. normal salt. II. acid salt.
(ii) Tetraoxosulphate (VI) acid and sodium hydroxide react to produce salt and water. Write a balanced chemical equation fir the formation of: I. a normal salt; II. an acid salt.
(b)(i) Explain briefly the term acid-base indicator.
(ii) Copy and complete the following table.

Indicator	, Colour in acidic medium	, Colour in basic medium
Methyl orange
Phenolphthalein

(iii) For each of the following titrations, state the most suitable indicator: I. strong acid against strong base; II. strong acid against weak base; iii. weak acid against strong base.
(c) Baking soda and hydrochloric acid react according to the following equation:
NaHCO\(_{3(aq)}\) + HCI\(_{(aq)}\) ---> NaCl\(_{(aq)}\) CO\(_{2(g)}\) + H\(_2\)O\(_{(l)}\). Calculate the mass of baking soda that would produce 10g of ccrbon (IV) oxide. [H = 1.00, C = 12.0, 0 = 16.0, Na = 23.0]
(d) Give a reason why a given mass of sodium hydroxide pellets cannot be used to prepare a standard solution.
NaHCO\(_3\) + HCI --> NaCI + CO\(_2\) + H\(_2\)O
84g NaHCO\(_3\) --> 44g CO\(_2\)
Xg --> 10g CO\(_2\)
Xg = \(\frac{84 \times 10}{44}\)
= 19.09g
= 19.1g.
(d) give a reason why a given mass of sodium hydroxide pellets cannot be used to prepare a standard solution: Sodium hydroxide absorbs water/deliquescent and absorbs carbon IV oxide from air/and this would make mass taken unreliable/add to its mass.