Post Utme Chemistry Past Questions and Answers

Question 116:

Temporary hardness of water is removed by the use of the following EXCEPT

A. Boiling
B. Use \(\mathrm{Ca}(\mathrm{OH})_{2}\)
C. Use of \(\mathrm{Na}_{2} \mathrm{CO}_{3}\)
D. Use of alum

Question 117:

Hydration of ions in solution is associated with ____________

A. Liberation of heat
B. Absorption of heat
C. Reduction of heat
D. Conduction of heat

Question 118:

Apiece of radioactive element has initially \(8.0 \times 10^{27}\) atoms. Halflife is two days. After 16 days the number of atoms is ____________

A. \(5 \times 10^{21}\)
B. \(5 \times 10^{22}\)
C. \(2 \times 10^{22}\)
D. \(2 \times 10^{21}\)

Question 119:

Which of the following pairs of substances are hygroscopic?

A. \(\mathrm{CaCl}\) and \(\mathrm{NaOH}\)
B. \(\mathrm{CaO}\) and \(\mathrm{KOH}\)
C. Conc. \(\mathrm{H}_{2} \mathrm{SO}_{4}\) and \(\mathrm{MgCl}_{2}\)
D. \(\mathrm{CuO}\) and \(\mathrm{CaO}\)

Question 120:

Zinc is not regarded as a transition metal even though it is a d-block element because ____________

A. It has no election in \(3 d\)-orbitals
B. It has all 3d-orbitals completely filled
C. It blends with other neighbouring elements
D. It does not form complex ions like others