Post Utme Chemistry Past Questions and Answers

Question 76:

In the manufacture of soap industrially, brine is used to ____________ the acid salt.

A. Oxidise
B. Reduce
C. Bleach
D. Precipitate

Question 77:

Methane gas can be made from carbon (II) oxide gas according to the equation \(2 \mathrm{CO}(\mathrm{g})+2 \mathrm{H}_{2}(\mathrm{~g}) rightarrow \mathrm{CH}_{4}(\mathrm{~g})+\mathrm{CO}_{2}(\mathrm{~g})\). Calculate the mass of \(\mathrm{CO}\) required to produce \(8.75 \times 10^{25}\) molecules of \(\mathrm{CH}_{4}\) ? \{At masses: \(\mathrm{C}=12.011, \mathrm{H}=1.008, \mathrm{O}=15.999\), Avogadro's no: \(6.022 \mathrm{x}\) \(10^{23}\) molecules /mole. \(\}\)

A. \(8140 \mathrm{~g}\)
B. \(4070 \mathrm{~g} \quad\)
C. \(1600 \mathrm{~g} \quad\)
D. \(32.00 \mathrm{~g} \quad\)
E. \(20.35 \mathrm{~g}\)

Question 78:

Potassium ethanoate is formed when ____________

A. Methanoic acid reacts with \(\mathrm{KOH}\)
B. Ethanoic acid reacts with \(\mathrm{KOH}\)
C. Methanol reacts with \(\mathrm{KCO}_{3}\)
D. Ethanol reacts with \(\mathrm{CH}_{3} \mathrm{COOH}\)

Question 79:

Saponification is defined as ____________

A. Acidic hydrolysis of fat or oil
B. Alkali hydrolysis of fat or oil
C. Condensation of two monomer units
D. Mixture of glacial ethanoic acid and excess of simple alkanol

Question 80:

Addition of water to calcium oxide leads to ____________

A. A physical change
B. A chemical change
C. The formation of a mixture
D. An endothermic reaction