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 $2.5atm$. The partial pressure of helium is ____________

A. $4.0atm$
B. $0.8atm$
C. $3.33atm$
D. $6.67atm$

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:

$C_4{H}_2+{90}_2\to 6C{O}_2+6H_{2}O$.
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 $512c{m}^3$ sample of a gas weighed $1.236g$ at ${20}^{\circ }C$ and a pressure of one atmosphere. The relative molecular mass of the gas is $[R=8.314K^{-1}mo{l}^{-1};1atm=101,325J{m}^{-3}]$.

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