Question 246:

• JAMB 1981

Which of the following compounds and elements would sublime on exposure to the atmosphere?

A. Ice
B. Sulphur
C. Phosphurous
D. Iodine
E. Potassium iodie

Question 247:

• JAMB 1981

When hydrogen sulphide and sulphur dioxide are each passed in turn into a solution of potassium dichromate?

A. Both gases change the colour of the solution from yellow to colourless
B. Both gases causes sulphur to be deposited
C. Only hydrogen sulphide decolourizes the solution
D. Only sulphur dioxide deposits sulphur
E. Only hydrogen sulphide deposits sulphur

Question 248:

• JAMB 1981

Which one of the following metals is not normally extracted by chemical reduction because of its position in the electrochemical series?

A. Copper
B. Iron
C. Lead
D. Potassium
E. Zinc

Question 249:

• JAMB 1981

If one mole of aluminium contains 6 x 10²³ atoms of aluminium, how many atoms are contained in 0.9g of aluminium?
(Al = 27)

A. 1.0 x 10²¹
B. 6.6 x 10²¹
C. 2.0 x 10²²
D. 1.0 x 10²²
E. 5.4 x 10²³

Question 250:

• JAMB 1981

4g each of aluminium foil and aluminium powder were introduced respectively into flasks P and Q.
Flask P was treated with warm bench sodium hydroxide and all the aluminium dissolved in one hour. Flask Q was treated with cold sodium hydroxide and all the aluminium dissolved in 10 minutes. What was responsible for Q reacting faster than P?

A. There were more aluminium atoms in Q than P
B. The heat given off in retarded the reaction
C. Q generated more pressure than P during the reaction
D. P generated more pressure than Q
E. Q has a greater surface area for the reaction than P