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Chemistry WAEC Past Questions

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1436

(a) State the type of reaction involved in the conversion of:

(i) proteins.to amino acids:

(ii) ethanol to ethene;

(iii) benzene to bromobenzene

 

(b) Write an equation to show that ethene reasts with hydrogen in the presence of finely divided nickel.

 

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1437

(a) Name the device used for producing an electric current from a chemical

(b) Copy and complete the table below.

Electrolyte

Product at the anode (carbon)

Product at the cathode (carbon)

Dilute NaCl\(_{(aq)}\)

Concentrated NaCI\(_{(aq)}\)

   

 

 

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1438

(a) Mention the chemical substance manufactured starting from each of the foirownc sets of materials:

(i) sugar and yeast;

(ii) ammonia, air and water;

(iii) vegetable oil and caustic alkali.

 

(b) State one air pollutant generated during the manufacture of fertilizers.

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1439

(a) What is the change in oxidation state of chromium in the reaction represented by the following equation?

3SO\(_2\) + Cr\(_2\)O\(^2_{-7}\) + 2H\(^+\)  -> 3SO\(_4^{2-}\) + 2Cr\(^{3+}\) + H\(_2\)O

(b) Use the half equations given below to deduce the equation for the reaction between iron(II) ions and heptaoxodichromate (VI) ions in acidic solution.

Fe\(^{2+}\)  --> Fe\(^{3+}\) + e\(^-\)

Cr\(_2\)O\(^{2-}_7\) + 14H\(^+\) + 6e\(^-\) ----> 2Cr\(^{3+}\) + 7H\(_2\)O.

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1440

(a) Mention one process apart from respiration, which increases the amount of carbon (IV) oxide in the atmosphere.

(b)(i) State one use of sodium hydrogentrioxocarbonate (IV).

(ii) Write an equation to show the action of heat on sodium hydrogentrioxocarbonate(IV).

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