Post Utme Obafemi Awolowo University Chemistry Past Questions and Answers

Question 1:

The isomer of a compound \(C _{5} H _{10}\) which does NOT decolorize bromine water is ____________

A. \(2-\) methylbutane
B. 2,2, -dimethylpropane
C. 2 - methylbut - 1 - ene
D. Methylcyclobutane

Question 2:

A mixture of nitrogen, oxygen and helium contains \(0.25\), \(0.15\) and \(0.4\) mole of these gases respectively. If the pressure contribution due to oxygen was \(2.5 atm\). The partial pressure of helium is ____________

A. \(4.0 atm\)
B. \(0.8 atm\)
C. \(3.33 atm\)
D. \(6.67 atm\)

Question 3:

Elements \(P\) has an atomic number of 12 while element \(Q\) has an atomic number 15. Combination of \(P\) and \(Q\) gave a compound \(P _{m} Q _{n}\). the respective values of \(m\) and \(n\) are ____________

A. 2 and 2
B. 2 and 3
C. 3 and 2
D. 2 and 1

Question 4:

\(C _{4} H _{2}+90_{2} \rightarrow 6 CO _{2}+6 H _{2} O\).
The hydrocarbon, \(C _{x} H _{2}\), in the reaction above is most likely ____________

A. An alkane
B. A benzene
C. An alkene
D. An alkyne

Question 5:

A \(512 cm ^{3}\) sample of a gas weighed \(1.236 g\) at \(20^{\circ} C\) and a pressure of one atmosphere. The relative molecular mass of the gas is \(\left[R=8.314 K ^{-1} mol ^{-1} ; 1 atm =101,325 Jm ^{-3}\right]\).

A. 58.07
B. 588,367
C. 5.88
D. 197.9