Chemistry, 1979, JAMB Exam, Exam, Paper 1 | Objectives

Paper Info

Year :

1979

Title :

Chemistry

Exam :

JAMB Exam

Paper 1 | Objectives

21 - 30 of 49 Questions

#	Question	Ans
21.	0.1 Faraday of electricity was passed through a solution of copper (ll) sulphate. The maximum weight of copper deposited on the cathode would be [Cu = 64] A. 64.0g B. 32.0g C. 16.0g D. 6.4 g E. 3.2g Show Content Detailed Solution CuSO₄ \(\to\) Cu²⁺ + SO₄²⁺ Cu²⁺ + 2e \(\to\) Cu 1 Faraday will deposit \(\frac{64}{2}\)gms of copper 0.1 faraday will deposit \(\frac{64}{2} \times \frac{1}{10} = \frac{64}{20}\) = \(\frac{32}{10}\) = 3.2gms	E
22.	Which one of these compounds will NOT give an oxygen gas on heating? A. Manganese dioxide B. Hydrogen peroxide C. Zinc nitrate D. Sodium nitrate E. Ammonium nitrate	E
23.	In the extraction of aluminum from purified bauxite by electrolysis, cryolite is used because A. it makes bauxite a better conductor of electricity B. it makes bauxite melt at a lower temperature C. it makes aluminium purer D. it prevents aluminium from getting oxidized E. it protects the carbon electrodes used in the process Show Content Detailed Solution The bauxite is purified to yield a white powder, aluminium oxide, from which aluminium can be extracted. The extraction is done by electrolysis. ... Instead, it is dissolved in molten cryolite, an aluminium compound with a lower melting point than aluminium oxide.	B
24.	In the redox reaction 2Fe²⁺ + CI₂ → 2Fe ^{3 +} + 2Cl A. Cl₂ is reduced because it has lost electrons B. Cl₂ is reduced because its oxidation number has decreased C. Cl₂ is reduced because its molecule is change to two ions D. Fe²⁺ is reduced because it has lost electrons E. Fe²⁺ is reduced because it has gained electrons	B
25.	An anhydride is? A. a compound wich has no water of crystallization B. an oxide whose solution in water has a PH greater than 7 C. an oxide whose solution in water has a PH less than 7 D. an oxide that has hydrogen atoms E. an amphoteric oxide	A
26.	In which of the following reactions is sulphur dioxide acting as an oxidizing agent? A. SO ₂ + 2HNO₃ →H₂SO₄ + NO₂ + Heat B. 2SO₂ + 2H₂O + O₂→ 2H₂SO₄ C. SO₂ + 2H₂O + CI₂→ H₂SO₄ + 2HCI D. SO₂ + 2H₂S → 3S + 2H₂O E. SO₂ + H₂O → H₂SO₃	D
27.	Calcium hydroxide and ammonium chloride when heated together will give an important product. This compound may be obtained dry by A. dissolving it in water, recrystallizing it and then drying in the oven B. passing it through a concentrated aqueous solution of sodium hydroxide C. passing it through calcium oxide D. passing it through concentrated sulphuric acid E. passing it through anhydrous calcium choride	C
28.	Starch can be converted to ethyl alcohol by A. distillation B. fermentation C. isomerization D. cracking E. cooking	B
29.	The reaction between hydrogen and iodine may be represented by the equation H₂(g)+ I₂(g) → 2HI(g), and is exothermic. Therefore A. an increase in temperature favours the forword reaction B. an increase in pressure favours the backward reaction C. both pressure and temperature muct be increased to favour the forward reaction D. a decrease in temperature will favour the forward reaction E. a decrease in pressure and an increase in temperature will favour the forward reaction	D
30.	Weighed salts Y and Z were left exposed in the laboratory overnight. In the morning Y had gained weight, and Z had become liquid. What conclusion could be drawn about the nature of the two salts? A. Z is efflorescent B. Y and Z are efflorescent C. Y and Z are deliquescent D. Y and Z are hygroscopic E. Y is deliquescent Show Content Detailed Solution A deliquescent compound is a compound that, on exposure to the atmosphere, tends to absorb moisture from the atmosphere in large quantities. Hence, Y and Z are DELIQUESCENT.	C

21.	0.1 Faraday of electricity was passed through a solution of copper (ll) sulphate. The maximum weight of copper deposited on the cathode would be [Cu = 64] A. 64.0g B. 32.0g C. 16.0g D. 6.4 g E. 3.2g Show Content Detailed Solution CuSO₄ \(\to\) Cu²⁺ + SO₄²⁺ Cu²⁺ + 2e \(\to\) Cu 1 Faraday will deposit \(\frac{64}{2}\)gms of copper 0.1 faraday will deposit \(\frac{64}{2} \times \frac{1}{10} = \frac{64}{20}\) = \(\frac{32}{10}\) = 3.2gms	E
22.	Which one of these compounds will NOT give an oxygen gas on heating? A. Manganese dioxide B. Hydrogen peroxide C. Zinc nitrate D. Sodium nitrate E. Ammonium nitrate	E
23.	In the extraction of aluminum from purified bauxite by electrolysis, cryolite is used because A. it makes bauxite a better conductor of electricity B. it makes bauxite melt at a lower temperature C. it makes aluminium purer D. it prevents aluminium from getting oxidized E. it protects the carbon electrodes used in the process Show Content Detailed Solution The bauxite is purified to yield a white powder, aluminium oxide, from which aluminium can be extracted. The extraction is done by electrolysis. ... Instead, it is dissolved in molten cryolite, an aluminium compound with a lower melting point than aluminium oxide.	B
24.	In the redox reaction 2Fe²⁺ + CI₂ → 2Fe ^{3 +} + 2Cl A. Cl₂ is reduced because it has lost electrons B. Cl₂ is reduced because its oxidation number has decreased C. Cl₂ is reduced because its molecule is change to two ions D. Fe²⁺ is reduced because it has lost electrons E. Fe²⁺ is reduced because it has gained electrons	B
25.	An anhydride is? A. a compound wich has no water of crystallization B. an oxide whose solution in water has a PH greater than 7 C. an oxide whose solution in water has a PH less than 7 D. an oxide that has hydrogen atoms E. an amphoteric oxide	A

26.	In which of the following reactions is sulphur dioxide acting as an oxidizing agent? A. SO ₂ + 2HNO₃ →H₂SO₄ + NO₂ + Heat B. 2SO₂ + 2H₂O + O₂→ 2H₂SO₄ C. SO₂ + 2H₂O + CI₂→ H₂SO₄ + 2HCI D. SO₂ + 2H₂S → 3S + 2H₂O E. SO₂ + H₂O → H₂SO₃	D
27.	Calcium hydroxide and ammonium chloride when heated together will give an important product. This compound may be obtained dry by A. dissolving it in water, recrystallizing it and then drying in the oven B. passing it through a concentrated aqueous solution of sodium hydroxide C. passing it through calcium oxide D. passing it through concentrated sulphuric acid E. passing it through anhydrous calcium choride	C
28.	Starch can be converted to ethyl alcohol by A. distillation B. fermentation C. isomerization D. cracking E. cooking	B
29.	The reaction between hydrogen and iodine may be represented by the equation H₂(g)+ I₂(g) → 2HI(g), and is exothermic. Therefore A. an increase in temperature favours the forword reaction B. an increase in pressure favours the backward reaction C. both pressure and temperature muct be increased to favour the forward reaction D. a decrease in temperature will favour the forward reaction E. a decrease in pressure and an increase in temperature will favour the forward reaction	D
30.	Weighed salts Y and Z were left exposed in the laboratory overnight. In the morning Y had gained weight, and Z had become liquid. What conclusion could be drawn about the nature of the two salts? A. Z is efflorescent B. Y and Z are efflorescent C. Y and Z are deliquescent D. Y and Z are hygroscopic E. Y is deliquescent Show Content Detailed Solution A deliquescent compound is a compound that, on exposure to the atmosphere, tends to absorb moisture from the atmosphere in large quantities. Hence, Y and Z are DELIQUESCENT.	C