Waec Chemistry 2009 Past Questions and Answers

Question 51:

• WAEC 2009

The electron configuration of carbon atom in its excited state is [ ₆C]

A. 1s²2s ²2px¹2py ¹
B. 1s ² 2s ²2px ²2py^o
C. 1s¹2s²2px¹2py¹2pz¹
D. 1s ²2s¹2px¹2py¹2pz¹

Question 52:

• WAEC 2009

An important medical use of nuclear radiations is

A. Activation analysis
B. Carbon dating
C. Radiotherapy
D. Tissue regeneration

Question 53:

• WAEC 2009

Which of the following elements exhibits the same chemical properties as the atom \(\frac{35}{17}\)X? An element with

A. Atomic number 17
B. Atomic number 18
C. Mass number 35
D. Mass number 52

Question 54:

• WAEC 2009

Which of the following noble gases has electronic structure similar to that of N in NH ₃? [\(\frac{14}{7}\)N]

A. ₂He
B. ₁₀Ne
C. ₁₈Ar
D. ₃₆Kr

Question 55:

• WAEC 2009

(a)(i) Outline a suitable procedure for the preparation of ZnCl\(_2\) crystals stating from zinc granules.
(ii) Write a balanced equation for the reaction in (a)(i).
(b) Considei' the following solutions: Na\(_2\)SO\(_{4(aq)}\), CH3COOK\(_{(aq)}\), Pb(NO\(_3\))\(_{2(aq)}\) and MgCl\(_2\). Which of them has/have a pH
(i) greater than 7;
(ii) equal to 7;
(iii) less than 7?

(c)(i) Determine the oxidation number of Mn in I. MnO\(_2\); II. KMnO\(_4\).
(ii) State one laboratory use of each of the .compounds in (c)(i).
(d) Explain why oxidation and reduction processes are complementary.
(e) Consider the reaction represented by the equation: Fe\(_{(s)}\) + 2Ag\(^+_{(aq)}\) \(\to\) Fe\(^{2+}_{(aq)}\) + 2Ag\(_{(s)}\)
(i) Write a balanced ionic half equations for the reaction.
(ii) Which of the species is I. oxidized; II. reduced?
(iii) State the change in the oxidation number of silver during the reaction.