Chemistry 2009 Objective — Question 1
The following are metals except
- A. siliconCorrect
- B. tin
- C. lead
- D. chromium
Explanation
Silicon is a metalloid (semi-conductor), not a true metal, unlike tin, lead and chromium.
Post-UTME Chemistry 2009 Objective Past Questions
All 16 questions from the Post-UTME Screening (Post-UTME) Chemistry 2009 Objective paper, with the correct answer and a full explanation for each. Free, no signup needed.
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Chemistry 2009 Objective — Question 2
Which of the following statements is true?
- A. All ammonium salts are soluble in waterCorrect
- B. All trioxocarbonate(IV) salts are soluble in water
- C. Some trioxonitrate (V) salts are soluble in water
- D. a and c above
Explanation
All ammonium salts are soluble in water; this is a well-established solubility rule (all nitrates, including trioxonitrates, are also soluble - not merely 'some' - which is why option A alone is the cleanest true statement).
Chemistry 2009 Objective — Question 3
Water was added to sodium dioxonitrate (V) salt in a test tube and the test tube became cold. The reaction is
- A. Reversible
- B. Exothermic
- C. endothermicCorrect
- D. explosive
Explanation
The test tube becoming cold indicates heat was absorbed from the surroundings, i.e. an endothermic reaction.
Chemistry 2009 Objective — Question 4
Which of the following is an alloy of aluminium?
- A. brass
- B. Bronze
- C. Gelena
- D. magnaliumCorrect
Explanation
Magnalium is an alloy of aluminium and magnesium.
Chemistry 2009 Objective — Question 5
Which of the following is an alkyne?
- A. C3H4
- B. C10H21
- C. C4H6Correct
- D. C6H12
Explanation
Alkynes follow the general formula CnH2n-2; for C4H6, n=4 gives 2(4)-2=6, matching.
Chemistry 2009 Objective — Question 6
Pick out the odd compound
- A. Toluene
- B. Phenol
- C. ethanolCorrect
- D. benzene
Explanation
Toluene, phenol and benzene are all aromatic (benzene-ring) compounds, while ethanol is a simple aliphatic alcohol unrelated to the benzene ring.
Chemistry 2009 Objective — Question 7
Which of the following zones is NOT part of a non-luminous Bunsen flame?
- A. Blue zone
- B. UnburntCorrect
- C. (further options not fully captured)
- D. (further options not fully captured)
Explanation
A non-luminous flame has recognized zones (e.g. blue zone, dark/unburnt gas cone in the centre, outer luminous mantle); the exact remaining options for this item were not fully legible in the scan.
Chemistry 2009 Objective — Question 8
Which of the following decomposition equations is correct?
- A. Ag2CO3 -> Ag2O + CO2Correct
- B. 2PbCO3 -> 2Pb + 2CO2 + O2
- C. 2NaNO3 -> 2NaNO2 + O2
- D. Ag2CO3 -> AgO2 + CO2
Explanation
Silver carbonate decomposes on heating to silver oxide and carbon dioxide, a correctly balanced equation.
Chemistry 2009 Objective — Question 9
In the reaction of aqueous solution of HCl and NaOH, the heat change is heat of
- A. solution
- B. neutralizationCorrect
- C. formation
- D. Displacement
Explanation
An acid-base reaction producing water and a salt releases the heat of neutralization.
Chemistry 2009 Objective — Question 10
Which of the following gas is colourless and odourless?
- A. NO2
- B. N2OCorrect
- C. O3
- D. b and c
Explanation
N2O (nitrous oxide) is colourless, though it has a faint sweetish odour; this item's precise intended answer was not fully clear from the scan, and is flagged accordingly.
Chemistry 2009 Objective — Question 11
The two hydrocarbons used as lower and upper standards for petrol are
- A. isooctane and benzene
- B. heptane and 2,2,6-trimethylpentane
- C. heptane and 2,2,4-trimethylpentaneCorrect
- D. heptane and neopentane
Explanation
Heptane (0 octane rating) and 2,2,4-trimethylpentane/isooctane (100 octane rating) are the standard reference fuels for octane rating.
Chemistry 2009 Objective — Question 12
Benzene commonly undergoes ----- reactions.
- A. addition
- B. elimination
- C. substitutionCorrect
- D. Amendment
Explanation
Benzene's aromatic ring stability favours substitution reactions over addition.
Chemistry 2009 Objective — Question 13
Under high pressure, real gases deviate from compliance with gas laws because their molecules
- A. experience repulsive forcesCorrect
- B. have become more energetic
- C. have become less energetic
- D. collide inelastically
Explanation
At high pressure, gas molecules are forced close enough together that repulsive intermolecular forces become significant, causing deviation from ideal gas behaviour.
Chemistry 2009 Objective — Question 14
Which of the 3d, 4s, 4p, 4d has the lowest energy?
- A. 3d
- B. 4sCorrect
- C. 4p
- D. 4d
Explanation
By the Aufbau filling order, the 4s orbital is filled before 3d, reflecting its lower energy at this point.
Chemistry 2009 Objective — Question 15
One of the causes of algae growth in rivers is the presence of
- A. heavy metals
- B. Pesticides
- C. Phosphates from detergentsCorrect
- D. High particulate loading
Explanation
Phosphates from detergents cause eutrophication, promoting excessive algae growth.
Chemistry 2009 Objective — Question 16
Phenolphthalein solution at pH 2.5 is
- A. yellow
- B. Pink
- C. red
- D. ColourlessCorrect
Explanation
Phenolphthalein is colourless in acidic solutions (below approximately pH 8.2).
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