All 19 questions from the Post-UTME Screening (Post-UTME) Chemistry 2006 Objective paper, with the correct answer and a full explanation for each. Free, no signup needed.
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Which of the following gases can be collected by the upward displacement of air?
Ammonia is significantly less dense than air, so it is commonly collected by upward displacement of air.
In the reaction IO3- + 5I- + 6H+ -> 3I2 + 3H2O, the oxidizing agent is
Iodine in IO3- is reduced (gains electrons), making IO3- the oxidizing agent.
A cyclo alkane with the molecular formula CxH18 has
For a cycloalkane C9H18, multiple ring-size and substitution isomers exist; three is presented as the best estimate given limited context from the scan.
The electronic configuration of an element is 1s^2 2s^2 2p^6 3s^2 3p^5. How many unpaired electrons are there in the element?
This item's exact configuration/options combination could not be fully confirmed from the scan; presented with reduced confidence.
Which of the following ions is a pollutant in drinking water even in trace amounts?
Mercury ions are highly toxic even at trace concentrations.
Which of the following represents the type of bonding present in ammonium chloride molecule?
NH4Cl contains both a dative covalent bond (within NH4+) and an ionic bond (between NH4+ and Cl-).
The air around a petroleum refinery is most likely to contain
Petroleum refining emissions typically include sulphur dioxide, carbon dioxide and nitrogen oxides.
Which of the following is NOT true of boiling?
Boiling occurs only at a specific temperature (the boiling point), unlike evaporation which occurs at any temperature.
Which of the following salts can be prepared with decomposition.
This item's exact intended meaning was not fully clear from the scan; presented with reduced confidence.
Which pH value indicates a basic solution?
A pH above 7 indicates a basic (alkaline) solution; of the listed values, only 11 qualifies.
A measure of the degree of disorderliness in a chemical system is known as the
Entropy is the thermodynamic measure of disorder in a system.
Oxidation is the process of
Oxidation is defined as the loss of electrons.
The pollution from petroleum spillage in rivers and lakes can best be dispersed by
Detergents act as dispersants, breaking up oil spills to aid natural degradation.
A mixture of 12g of carbon and 64g of sulfur is heated until reaction is complete and none of the reactants is left over. What mass of the compound carbon II sulfide is formed?
Moles C = 12/12 = 1mol; moles S = 64/32 = 2mol, matching the 1:2 stoichiometry for C + 2S -> CS2. Moles CS2 = 1mol; molar mass CS2 = 76g/mol; mass = 76g.
Water is poured over a white solid and a colourless neutral gas is evolved which burns with a sooty flame. The white solid is
Calcium carbide reacts with water to give ethyne, which burns with a sooty flame.
A brand of ink containing cobalt (II) chloride and iron II ion scan be separated into its various components by
Chromatography is the standard technique for separating the different coloured components of an ink mixture.
Which of the following factors does NOT affect the rate of a chemical reaction between non gaseous reactants?
This item's fourth option was not fully legible in the scan; temperature, catalyst presence, and surface area are all recognized factors affecting reaction rate.
The complete oxidation of butane gives
Complete oxidation of a primary alcohol/aldehyde derived from butane ultimately yields the carboxylic acid, butanoic acid.
The main constituents of petroleum are
Petroleum is fundamentally a complex mixture of hydrocarbons (of which alkanes are just one class).
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