Jamb Chemistry 1993 Past Questions and Answers

Question 21:

• JAMB 1993

A reaction takes places spontaneously if?

A. ∆G = O
B. ∆S < O and ∆H > O
C. ∆H < T ∆S
D. ∆G > O

Question 22:

• JAMB 1993

The standard enthalpies of formation of CO_2(g), H₂O(g) and CO_(g) in kJ mol^- are -394, -242 and -110 respectively. What is the standard enthalpy change for the reaction CO_(g) + H_2(g)O → CO_2(g) + H_2(g)?

A. -42 KJ mol^-
B. +42 KJ mol^-
C. -262 KJ mol^-
D. +262 KJ mol^-

Question 23:

• JAMB 1993

10g of a solid is in equilibrium with its own vapour.
When 1 g of a small amount of solid is added, the vapour pressure?

A. Remains the same
B. Drops
C. Increases by 1%
D. Increases by 99%

Question 24:

• JAMB 1993

NaCI_(s) + H₂SO_4(I) → HCI_(g) + NaHSO_4(s).
In the reaction above, H₂SO₄ behaves as?

A. A strong acid
B. An oxidizing agent
C. A good solvent
D. A dehydrating agent

Question 25:

• JAMB 1993

Which of these gases can be dried with concentrated H2SO4?

A. HBr
B. H₂S
C. NH₃
D. SO₂