Post Utme Chemistry Past Questions and Answers

Question 291:

The separation of oil and water with different boiling points can best be achieved by ____________

A. Fractional distillation
B. Decantation
C. Evaporation
D. Using a separating funnel

Question 292:

Calculate the minimum volume of oxygen that is required for the complete combustion of a mixture of 20cm³ of CO and 25cm³ of hydrogen.

A. 45 cm³
B. 22.5cm³
C. 20 cm³
D. 10 cm³

Question 293:

An increase in temperature causes an increase in the pressure of a gas because there is an increase in the ____________

A. Average velocity of the gas molecules
B. Number of collisions between the gas molecules
C. Density of the gas molecules
D. Free mean path between each molecule and the other

Question 294:

A liquid begins to boil when ____________

A. Its vapour pressure is equal to the vapour pressure of its solid at a given temperature
B. Molecules start escaping from the surface
C. Its vapour pressure equals the atmospheric pressure
D. Its volume is slightly increased

Question 295:

If the relative rate of diffusion of a gas is 0.25 and that of Cl under the same condition is 0.20. Calculate the relative molecular mass of the gas.

A. 22.7
B. 45.4
C. 68.1
D. 90.8