Jamb Chemistry 2019 Past Questions and Answers

Question 86:

• JAMB 2019

Consider the reaction
A\(_{(s)}\) + 2B\(_{(g)}\) → 2C\(_{(aq)}\) + D\(_{(g)}\)
What will be the effect of a decrease in pressure on the reaction?

A. The equilibrium will shift
B. Rate of forward reaction will increase
C. Rate of backward reaction will increase
D. Rates of forward and backward reaction are not affected

Question 87:

• JAMB 2019

For the general equation of the nature
xP + yQ ⇌ mR + nS, the expression for the equilibrium constant is

A. K[P]\(^x\)[Q]\(^y\)
B. \(\frac{m[R][S]}{x[P]y[Q]}\)
C. \(\frac{[P]^x[Q]^y}{[R]^m[S]^n}\)
D. \(\frac{[R]^m[S]^n}{[P]^x[Q]^y}\)

Question 88:

• JAMB 2019

Which of the following reactions is an oxidation process?

A. 2H\(^+\) + 2e\(^-\) \(\to\) H\(_2\)
B. 2O\(^{2-}\) + 4e\(^-\) \(\to\) O\(_2\)
C. OCl\(^-\) + H\(_2\)O + 2e\(^-\) \(\to\) 2OH\(^-\) + Cl\(^-\)
D. Cl + e\(^-\) \(\to\) Cl\(^-\)

Question 89:

• JAMB 2019

If acidified Potassium Dichromate(VI) (K\(_2\)Cr\(_2\)O\(_7\)) acts as oxidizing agent, color changes from

A. Yellow to green
B. Orange to green
C. Yellow to red
D. Orange to red

Question 90:

• JAMB 2019

The heat of formation of ethene, C\(_2\)H\(_4\) is 50 kJmol\(^{-1}\), and that of ethane, C\(_2\)H\(_6\) is -82kJmol\(^{-1}\). Calculate the heat evolved in the process:
C\(_2\)H\(_4\) + H\(_2\) \(\to\) C\(_2\)H\(_6\)

A. -122kJ
B. -132kJ
C. -88kJ
D. -60kJ