Energy changes - Jamb Chemistry Past Questions and Answers

Question 21:

• JAMB 1986

The approximate volume of air containing 10cm³ of oxygen is?

A. 20 cm³
B. 25 cm³
C. 50 cm³
D. 100 cm³

Question 22:

• JAMB 1986

A white solid suspected to be lead trioxonitrate (V) zinc trioxocarbonate (IV) or calcium trioxocabonate (IV) was heated strongly. Its residue which was yellow when hot and white when cold is?

A. Lead (II) oxide
B. Calcium oxide
C. Zinc oxide
D. Lead nitrate

Question 23:

• JAMB 1988

The diagram above shows the reaction path of an exothermic reaction. The heat of reaction is represented by

A. L
B. Ll
C. Lll
D. LV

Question 24:

• JAMB 1990

In a reaction: \(SnO_{2} + 2C → Sn + 2CO\) the mass of coke containing 80% carbon required to reduce 0.302 kg of pure tin oxide is?
(Sn - 119, O - 16, C - 12).

A. 0.40 kg
B. 0.20 kg
C. 0.06 kg
D. 0.04 kg

Question 25:

• 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