Post Utme University of Port Harcourt Chemistry Past Questions and Answers

Question 11:

What weight of sodium hydroxide is required to make 500 cm³
of 0.2 M solution?
[Na=23, 0=16, H = 1]

A. 40g
B. 20g
C. 10g
D. 4g
E. 2g

Question 12:

\(60 \mathrm{~cm}^{3}\) of hydrogen are sparked with \(20 \mathrm{~cm}^{3}\) of oxygen at \(100^{\prime} \mathrm{C}\) and I atmosphere. The total volume of the residual gas is

A. \(60 \mathrm{~cm}^{3}\)
B. \(10 \mathrm{~cm}^{3}\)
C. \(40 \mathrm{~cm}^{3}\)
D. \(30 \mathrm{~cm}^{3}\)
E. \(70 \mathrm{~cm}^{3}\)

Question 13:

\(0.16 \mathrm{~g}\) of methane when burst raises the temperature of \(100 \mathrm{~g}\) of water by \(40^{\circ} \mathrm{C}\). What is the heat of combustion of methane if the heat capacity of water is \(4.2 \mathrm{Jkg}^{-}\) \({ }^{1} \mathrm{C}^{-1} ?\left[\mathrm{CH}_{4}=-16
ight]\)

A. \(1,160 \mathrm{kJmol}^{-1}\)
B. \(1,180 \mathrm{kJmol}^{-1}\)
C. \(1,560 \mathrm{kJmol}^{-1}\)
D. \(1,600 \mathrm{kJmol}^{-1}\)
E. \(1,680 \mathrm{kJmol}^{-1}\)

Question 14:

Hydrated salt of formula \(\mathrm{MSO}_{4} \cdot \mathrm{XH}_{2} \mathrm{O}\) contains \(45.3 \%\) by mass of water of crystallization. Calculate the value of \(X\).

\([M=56, S=32, O=16, H=1]\)

A. 3
B. 5
C. 7
D. 10

Question 15:

A given quantity of a gas occupies a volume of \(228 \mathrm{~cm}^{3}\) at a pressure of \(750 \mathrm{mmHg}\). What will be its volume at atmospheric pressure?

A. \(220 \mathrm{~cm}^{3}\)
B. \(225 \mathrm{~cm}^{3}\)
C. \(230 \mathrm{~cm}^{3}\)
D. \(235 \mathrm{~cm}^{3}\)