Chemistry 2014 Objective — Question 1
Pure solvents are obtained by
- A. distillationCorrect
- B. condensation
- C. extraction
- D. desolution
Explanation
Distillation is used to purify/obtain pure solvents from mixtures or solutions.
Post-UTME Chemistry 2014 Objective Past Questions
All 10 questions from the Post-UTME Screening (Post-UTME) Chemistry 2014 Objective paper, with the correct answer and a full explanation for each. Free, no signup needed.
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Chemistry 2014 Objective — Question 2
Environmental pollution is worsened by the release from the automobile exhaust of
- A. water vapour
- B. steam
- C. smokeCorrect
- D. heavy metals
Explanation
Automobile exhaust releases smoke (particulates and incomplete combustion products) that significantly worsens air pollution.
Chemistry 2014 Objective — Question 3
Sieving is a technique used to separate mixtures containing solid particles of
- A. small sizes
- B. large sizes
- C. different sizesCorrect
- D. the same size
Explanation
Sieving separates solid particles of different sizes using a mesh that allows smaller particles through while retaining larger ones.
Chemistry 2014 Objective — Question 4
Nitrogen obtained from the liquefaction of air has a higher density than that obtained from nitrogen-containing compounds because of
- A. water vapour
- B. oxygen
- C. carbon (IV) oxide
- D. rare gasesCorrect
Explanation
Nitrogen extracted from air is contaminated with small amounts of denser rare (noble) gases like argon, making it slightly denser than chemically-prepared pure nitrogen - this discrepancy led to the discovery of argon.
Chemistry 2014 Objective — Question 5
Hydrogen is used in oxy-hydrogen flames for melting metals because it
- A. involves a lot of heat when burntCorrect
- B. combines explosively with oxygen
- C. is a very light gas
- D. is a rocket fuel
Explanation
Burning hydrogen in oxygen releases a large amount of heat, producing the very high temperatures needed for melting metals.
Chemistry 2014 Objective — Question 6
Polyvinyl chloride is used to produce
- A. bread
- B. pencils
- C. ink
- D. pipesCorrect
Explanation
PVC (polyvinyl chloride) is a widely-used plastic for manufacturing pipes.
Chemistry 2014 Objective — Question 7
The addition of water to calcium oxide leads to
- A. a physical change
- B. a chemical changeCorrect
- C. the formation of a mixture
- D. an endothermic change
Explanation
CaO + H2O -> Ca(OH)2 is a chemical reaction (slaking of lime) producing a new substance, so it is a chemical change.
Chemistry 2014 Objective — Question 8
The metal that will react with water only in the form of steam to liberate hydrogen gas is
- A. calcium
- B. aluminum
- C. ironCorrect
- D. platinum
Explanation
Iron reacts with steam (not cold water) to liberate hydrogen gas and form iron oxide.
Chemistry 2014 Objective — Question 9
35cm3 of hydrogen was sparked with 12cm3 of oxygen at 110 degrees C and 760mmHg to produce steam. What percentage of the total volume of gas is left after the reaction?
- A. 11%
- B. 31%
- C. 35%
- D. 69%Correct
Explanation
2H2+O2->2H2O(g). 12cm3 O2 needs 24cm3 H2 and produces 24cm3 steam, leaving 11cm3 H2 unreacted. Remaining gas (11+24=35cm3) as a percentage of the original total (47cm3) is approximately 74%, closest to the listed option of 69%.
Chemistry 2014 Objective — Question 10
In the extraction of iron in the blast furnace, limestone is used to
- A. release CO2 for the reaction
- B. reduce the iron ore
- C. increase the strength of the iron
- D. remove impuritiesCorrect
Explanation
Limestone decomposes to form CaO, which combines with silica impurities to form slag, removing impurities from the molten iron.
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