Post Utme Chemistry Past Questions and Answers

Question 171:

An important ore of iron contains \(72.36 \%\) iron and \(27.64 \%\) oxygen. Determine its empirical formula

A. FeO
B. \(\mathrm{Fe}_{2} \mathrm{O}_{3}\)
C. \(\mathrm{Fe}_{3} \mathrm{O}_{4}\)
D. \(\mathrm{Fe}_{2} \mathrm{O}\)

Question 172:

Which of the following decreases when a given mass of gas is compressed to half its initial volume?

A. Average intermoleculardistance
B. Frequency of collision
C. Number of molecules present
D. Atomic radius of each particle

Question 173:

The densities of two gases \(X\) and \(\mathrm{Y}\) are \(2.5 \mathrm{gdm}^{-3}\) and \(10.0\) \(\mathrm{gdm}^{-3}\) respectively. What is the rate of diffusion of \(X\) relative to \(Y\) ?

A. \(1: 2.5\)
B. \(2.5: 1\)
C. \(1: 2\)
D. \(2: 1\)

Question 174:

The properties of elements are periodic functions of their ____________

A. Atomic number
B. Atomic radius
C. Atomic volume
D. Mass number

Question 175:

Which of the following solutions containing only hydroxyl ions will liberate hydrogen gas when reacted with Mg metals?

A. \(1.0 \times 10^{-5} \mathrm{moldm}^{-3}\)
B. \(1.0 \times 10^{-13} \mathrm{moldm}^{-3}\)
C. \(1.0 \times 10^{-3} \mathrm{moldm}^{-3}\)
D. \(1.0 \times 10^{-2} \mathrm{moldm}^{-3}\)