Waec Chemistry 2006 Past Questions and Answers

Question 26:

• WAEC 2006

Which of the following substance is an ore of iron?

A. Bauxite
B. Cassiterite
C. Haematite
D. Steel

Question 27:

• WAEC 2006

The ammonium compound used in the manufacture of dry cells is

A. NH₄NO₃
B. (NH₄)SO₄
C. NHCI₄
D. (NH₄)₂CO₃

Question 28:

• WAEC 2006

Which of the following equations represents a substitution reaction?

A. C ₂H_10(g) + CI _2(g) → C₄H₉ CI_(g) + HCI_(g)
B. C ₂H_4(g) + HCI _(g) → C ₂H₅ CI_(l)
C. C₂H_2(g) + 2H _2(g) → C ₂H_6(g)
D. C ₃H_4(g) + 40_2(g) → 3CO_2(g) + 2H ₂O_(g)

Question 29:

• WAEC 2006

a) Define each of the following terms and indicate one use of each:
(i) Nuclear fission; (ii) Nuclear fusion.
(b) Alpha particle emission by \(^{293}_{25}U\) proceduces an element A. Beta particle emission by the particle A produces another element B. Element B also undergoes alpha particle emission to produce \(^{227}_{89}AC\). Write balanced equations to represent the above statement.
(c) The models below represent the filling of orbitals in an atom.

State which rule(s) is/are violated or obeyed by each model.
(d) Explain why the boiling point of H\(_2\)S with relative molecular mass of 34 is lower than that of H\(_2\)O with relative molecular mass of 18.

(e) HCI is passed into each of the following solvents:
(i) water;
(ii) methylbenzene. I. State the effect of each solution on blue litmus paper II. Compare the electrical conductivities of the two solutions.

(f) Zinc dust is added to copper (II) tetraoxosulphate (VI) solution. State;
(i) what is observed; (ii) the type of reaction that occurs.

Question 30:

• WAEC 2006

(a)(i) State two differences betwecii the properties of solids and gases
(ii) What process does each of X, Y and Z represent in the changes shown below?


(b)(i) State Charles' Law (ii) Draw a sketch to graphically illustrate Charles' Law.

(c) 60 cm of hydrogen diffused through a porous membrane in 10 minutes. The same volume of a gas G diffused through the same membrane in 37.4 minutes. Determine the relative molecular mass of G. [ H = I ]

(d)(i) State two assumptions X of the kinetic theory.
(ii) Consider the reaction represented by the Solid of Liquid following equation:
H\(_{2(g)}\) + Cl\(_{2(g)}\) \(\to\) 2HCI\(_{(g)}\)
Use the kinetic theory to explain how the rate of formation of HCI\(_{(g)}\) would be affected by I. increase in temperature; II. decrease in pressure.

(e) Given different examples, mention one metal in each case vihich produces hydrogen on reacting with (i) dilute mineral acid; (ii) cold water; (iii) steam; (iv) hot, concentrated alkali.