All 10 questions from the Post-UTME Screening (Post-UTME) Chemistry 2008 Objective paper, with the correct answer and a full explanation for each. Free, no signup needed.
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Which of these metals, Mg, Fe, Pb and Cu will dissolve in dilute HCl if air is blown through the solution?
Only the more reactive metals (Mg, Fe) readily dissolve in dilute HCl under these conditions.
The name pentanone is not specific and proper because it can refer to
'Pentanone' is ambiguous since the carbonyl group could be at either the 2- or 3- position.
Which of the following have saturated isomers?
Per the source key, butane and pentane is the marked answer.
Which of these mathematical relationships is for Charles' law?
Charles' Law (at constant pressure) states V∝T, i.e. V=KT.
Powdered marble reacts faster with hydrochloric acid solution than the granular form because the powdered form has
A larger surface area means more contact between reactants, speeding up the reaction.
The pOH of a solution of 0.25 mol dm⁻³ of hydrochloric acid is
pH=-log(0.25)≈0.60; pOH=14-0.60≈13.40.
Sulphur (IV) oxide bleaches by
SO2 bleaches by reduction (removing oxygen/donating electrons to the coloured compound).
Carcinogenic substance is
Asbestos dust is a well-known carcinogen.
An element X forms a volatile hydride XH3 with a vapour density of 17.0. The relative atomic mass of X is
Relative molecular mass=2×vapour density=34; mass of X = 34-3(H)=31.
How many moles of limestone will be required to produce 5.6g of CaO?
CaCO3→CaO+CO2 is 1:1. Moles CaO=5.6/56=0.1mol, so 0.1mol limestone is needed.
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