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Chemistry WAEC Past Questions

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1651

Dilution factor is the?

  • A. amount of distilled water that is added to the concentrated solution to dilute it
  • B. Quantity of distilled water added to l dm\(^3\) of the concentrated solution to give the dilute solution
  • C. number of times the volume of the concentrated solution is diluted to give the dilute solution
  • D. act of diluting the concentrated solution to obtain the dilute solution
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1652

Calcium chloride is an ionic compound. Which of the following statements account for its ionic character?

I. Calcium has high ionization energy.  II. Calcium has low ionization energy. III. Chlorine has high electron affinity. IV. Chlorine has high Ionization energy.

  • A. I and Il only
  • B. I, II and IV only
  • C. II, IIl and IV only
  • D. I, II, III and IV
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1653

An example of a biodegradable pollutant is?

  • A. plastic
  • B. sewage
  • C. carbon (II) oxide
  • D. hydrogen sulphide
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1654

(a)(i) State Faraday's first law of electrolysis. (ii) Distinguish between a strong electrolyte and a weak electrolyte

(b) State one chemical property of ethyne.

(c)( i) What is meant by the tern unsaturated hydrocarbon? (ii) Complete the following reaction equation: CH\(_3\) + CH\(_3\)OH-> (iii) Name the major product formed in the cation stated in 1(c)(ii).

(d) State one way by which the rate of esterification could be increased.

(e) Consider the reaction represented by the following equation: Zn + H\(_2\)SO4 → ZnOS\(_4\) + H\(_2\) . If 3.75g of Zn dust was added to excess H\(_2\)SO\(_4\). Calculate the number of molecules of hydrogen gas produced. [ Zn = 65.0, Na = 6.02 X10\(^23\) ].

 (f) State one effect of global warming.

(g) Consider the following reaction equation:

A. Pb(NO\(_3\)) +H\(_2\)S --> PbS + 2HNO\(_3\);

B. H\(_2\) + C\(_2\)H\(_4\) → C\(_2\)H\(_6\).

C. Zn(OH)\(_2\) + 2OH → [ Zn(OH)\(_4\) ]\(^2\).

(i)  Which of the equations represent(s) redox process? (ii) State the change in Oxidation number of the species that are oxidized or reduced. (h)(i) State two of the main concepts of Bohr's model of the atom. (ii) State the limitations of Bohr's model. (i) List three factors that could influence the equilibrium position of a reversible reaction. (j) Calcium trioxocarbonate(iv) powder is added to separate equimolar solutions of hydrochloric acid and ethanoic acid. State one: (i) similarity in the observation in both reactions: (ii) difference in the observation in both reactions.

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1655

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(a) Consider the following compounds:  (i) What is the relationship between the compounds labeled A and B? (ii) Name each of compounds A and B. (iii) Will the chemical properties of compounds A and B be the same? (iv) Give the reason for the answer stated in 2(a)(ii).

(b)(i) Give two characteristic features of boiling, (ii) What would be the effect of each of the following conditions on the boiling point of water? I. Addition of crystals of sodium chloride. II. Reduction of the atmospheric pressure. (iii) State one way in which boiling differs from evaporation.

(c)(i) Differentiate between an unsaturated solution and a saturated Solution. (ii) State two ways by which a saturated solution could be made to dissolve more solute. (iii) State one factor that could affect the solubility of a solid in a liquid. (d)(i) Define the term mole .

(ii) Consider the following reaction equation: MgO + 2HCI → MgCl\(_2\) + H\(_2\). What mass of magnesium Oxide is needed to neutralize 25.0 cm3 of 0.1 mol dm-3 hydrochloric acid? [O= 16.0; Mg = 24.0]. (e) State three physical properties of metals.

 

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