Post Utme Chemistry Past Questions and Answers

Question 286:

Which of the following is an example of a mixture

A. Common salt
B. Washing soda
C. Sand
D. Blood

Question 287:

Which of following is correct of the change in oxidation number of phosphorus from \(4 \mathrm{P}\) to \(2 \mathrm{p}_{2} \mathrm{O}_{5}\) ?

A. 0 to \(+5\)
B. 0 to \(+2\)
C. 4 to \(+5\)
D. 4 to \(-2\)

Question 288:

Two \(50 \mathrm{~cm}^{3}\) cylinders I and II contain hydrogen and oxygen respectively at the same temperature and pressure. If there are 3.0 moles of oxygen then the mass of hydrogen is

A. 3g
B. 6g
C. 9g
D. 12g

Question 289:

A good method of cleaning up freshly-spilled oil which has not spread over a large surface of water is by ____________

A. Spraying with hot water
B. Dispersal with compressed air
C. Burning off the oil layer
D. Disinfection with chlorine

Question 290:

Hardness of water is mainly due to the presence of ____________

A. Calcium hydroxide or magnesium hydroxide
B. Calcium trioxocarbonate (IV) or calcium tetraoxosulphate (VI)
C. Sodium hydroxide or magnesium hydroxide
D. Calcium chloride or sodium chloride salts