Chemistry 2010 Objective — Question 1
What is the atomic number of an element if its atom contains 10 protons, 10 electrons and 12 neutrons?
- A. 32
- B. 22
- C. 20
- D. 10Correct
Explanation
Atomic number equals the number of protons, which is 10.
Post-UTME Chemistry 2010 Objective Past Questions
All 11 questions from the Post-UTME Screening (Post-UTME) Chemistry 2010 Objective paper, with the correct answer and a full explanation for each. Free, no signup needed.
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Chemistry 2010 Objective — Question 2
The loss of water of crystallization to the atmosphere by some crystalline salts is known as....
- A. EfflorescenceCorrect
- B. effervescence
- C. Deliquescence
- D. Phosphorescence
Explanation
Efflorescence is the loss of water of crystallization from a hydrated salt exposed to air.
Chemistry 2010 Objective — Question 3
Carbon is often deposited in the exhaust pipe of cars because of the.....
- A. dehydrogenation of petrol
- B. incomplete combustion of petrolCorrect
- C. presence of additives
- D. presence of carbon in petrol
Explanation
Incomplete combustion of petrol (hydrocarbon fuel) produces soot/carbon deposits.
Chemistry 2010 Objective — Question 4
Plastics are polymers whose production techniques involve all except....
- A. high pressure
- B. low pressure
- C. SaltingCorrect
- D. high temperature
Explanation
'Salting' is not a recognized plastic production/polymerization technique, unlike pressure and temperature control.
Chemistry 2010 Objective — Question 5
Which of the following gases is produced when ammonium trioxonitrate (v) is heated with sodium hydroxide?
- A. Oxygen
- B. AmmoniaCorrect
- C. Nitrogen (IV) oxide
- D. Hydrogen
Explanation
Heating an ammonium salt with NaOH releases ammonia gas.
Chemistry 2010 Objective — Question 6
How many grammes of HCl will be required to react with 10g of NaOH (H=1, Cl=35.5, Na=23, O=16)?
- A. 9.125gCorrect
- B. 4.6g
- C. 10.1g
- D. 18.4g
Explanation
Moles NaOH = 10/40 = 0.25mol. HCl + NaOH -> NaCl + H2O (1:1). Moles HCl = 0.25mol; mass = 0.25 x 36.5 = 9.125g.
Chemistry 2010 Objective — Question 7
The bond formed between H2O and H+ to form the hydroxonium ion is —
- A. co-ordinate covalencyCorrect
- B. electrovalent
- C. Covalent
- D. Ionic
Explanation
The lone pair on the oxygen atom of water is donated to H+, forming a coordinate (dative) covalent bond.
Chemistry 2010 Objective — Question 8
Common salt is dissolved in water and the mixture is evaporated. The vapour given off is condensed. The condensed vapour is a..,.
- A. solute
- B. Suspension
- C. solventCorrect
- D. Solution
Explanation
The vapour driven off and condensed is water, the solvent, leaving behind the solute (salt).
Chemistry 2010 Objective — Question 9
When some substances are heated, they change directly into gases without appearing in the liquid state. An example is....
- A. copper
- B. iodineCorrect
- C. sodium
- D. Sulphur
Explanation
Iodine sublimes directly from solid to gas on heating, without passing through a liquid phase.
Chemistry 2010 Objective — Question 10
What is the IUPAC name of the compound KMnO4?
- A. Potassium manganate
- B. Potassium tetraoxomanganate (VII)Correct
- C. Potassium trioxomanganate (IV)
- D. Potassium oxomanganate (IV)
Explanation
KMnO4 has manganese in the +7 oxidation state with 4 oxygen atoms, giving the IUPAC name potassium tetraoxomanganate(VII).
Chemistry 2010 Objective — Question 11
The formation of clouds results directly from....
- A. vaporization
- B. fusion
- C. CondensationCorrect
- D. Sublimation
Explanation
Clouds form as water vapour condenses into tiny droplets in the atmosphere.
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