Chemistry 1990 Jamb Past Questions and Answers

Question 6 :

• JAMB 1990

Fe\(_2\)O\(_{3(s)}\) + 2Al\(_{(s)}\) → Al\(_2\)O\(_3\) + 2Fe\(_{(s)}\). If the heats of formation of Al\(_2\)O\(_3\) and Fe\(_2\)O\(_3\) are - 1670 kJmol\(^{-1}\) and - 822 kJmol\(^{-1}\) respectively, the enthalpy change in kJ for the reaction is ?

A. +2492
B. +848
C. -848
D. -2492

Question 7 :

• JAMB 1990

Iron galvanized with zinc is cathodically protected from corrosion. This is because?

A. Zinc has a more positive oxidation potential than iron
B. Zinc has less positive oxidation potential than iron
C. Bith have the same oxidation potential
D. Zinc is harder than iron

Question 8 :

• JAMB 1990

Which of the following samples will react fastest with dilute trioxonitrate (V) acid?

A. 5 g of lumps of CacO₃ at 25°C
B. 5 g of powered CacO₃ at 25°
C. 5 g of lumps of CaCO₃ at 50°C
D. 5 g of powered CaCO₃ AT 50°C

Question 9 :

• JAMB 1990

In the reaction:
2Hl_(g) ↔ H_2(g) + l_2(g)' ΔH = 10 kj;
The concentration of iodine in the equilibrium mixture can be increased by?

A. Raising the pressure
B. Raising the temperature
C. Adding a catalyst
D. Lowering the pressure

Question 10 :

• JAMB 1990

Which of the following gases can be collected by the upward displacement of air?

A. NO
B. H ₂
C. NH₃
D. Cl ₂