Waec Chemistry 2012 Past Questions and Answers

Question 16:

• WAEC 2012

Consider the following reaction equation: CaCO\(_{3(s)}\) + 2HCI\(_{(aq)}\) → CaCl\(_{2(aq)}\) + H\(_2\)O\(_{(l)}\) + CO\(_{2(g)}\). What mass of CaCI\(_2\) would be obtained when 25.0g of CaCO\(_{3(s)}\) is reacted with excess HCI\(_{(aq)}\)? [CaCO\(_3 = 100; CaCI\(_2\) = 111]

A. 4.00g
B. 4.44 g
C. 18.9 g
D. 27.8 g

Question 17:

• WAEC 2012

The number of sulphur atoms in 3.20g of SO\(_{2(g)}\) is [O = 16.0;S = 32.0; Avogadro constant = 6.02 x 10\(^{23}\)]

A. 3.01 x 10²²
B. 6.02 x 10²²
C. 6.02 x10²³
D. 1.20 x 10²⁴

Question 18:

• WAEC 2012

Consider the reaction represented by the following equation: xCH\(_3\)OH + yO\(_2\) → 2CO\(_2\) + zH\(_2\)O. The values of x,y and z respectively, are

A. 2,3 and 4
B. 2, 4 and 3
C. 1,2 and 3
D. 1, 3 and 5

Question 19:

• WAEC 2012

The formula of mercury (l) dioxonitrate (III) is

A. HgNO₃
B. Hg₂NO₂
C. Hg₂(NO₂)₂
D. Hg(NO₃)₂

Question 20:

• WAEC 2012

A sample of a gas may be identified as chlorine if it turns

A. Damp blue litmus paper red
B. Lime water miky
C. Lead ethanoate paper black
D. Starch iodide paper blue-black