Post Utme Chemistry Past Questions and Answers

Question 11:

\(200 \mathrm{~cm}^{3}\) of air was passed over heated copper in a syringe several times to produce copper (II) oxide. When cooled, the final volume of air recorded was \(158 \mathrm{~cm}^{3}\). Estimate the percentage of oxygen in the air.

A. \(31 \%\)
B. \(27 \%\)
C. \(21 \%\)
D. \(19 \%\)

Question 12:

\(30 \mathrm{~cm}^{3}\) of oxygen at 10 atmosphere pressures is placed in a \(20 \mathrm{dm}^{3}\) container. Calculate the new pressure if temperature is kept constant.

A. \(6.7\) atm
B. \(15.0\) atm
C. \(60.0\)
D. \(66.0\)

Question 13:

Bond dissociation energy of \(500 \mathrm{KJ} \mathrm{mol}^{-1}\) may be assigned to ____________

A. Ionic bonding
B. Covalent bonding
C. Hydrogen bonding
D. Metallic bonding
E. Van-der-waals bonding

Question 14:

A mixture of iron and sulphur can be separated by dissolving the mixture in ____________

A. Steam
B. B dilute hydrochloric acid
C. Dilute sodium hydroxide
D. Benzene

Question 15:

A mixture of sand, ammonium chloride and sodium chloride is best separated by

A. Sublimation followed by addition of water and filtration
B. Sublimation followed by addition of water and evaporation
C. Addition of water followed by filtration and sublimation
D. Addition of water followed by crystallization and sublimation