Oxidation And Reduction - Chemistry Jamb Past Questions and Answers

Question 36 :

• JAMB 1989

An element, Z froms an anion whose formula is [Z(CN)₆]^y. If Z has an oxidation number of +2, what is the value of y?

A. - 2
B. - 3
C. - 4
D. - 5

Question 37 :

• JAMB 1989

The combustion of ethene, C ₂H ₄, is given by the equation C ₂H ₄ + 30 ₂ → 2CO₂ + 2H₂ O; ∆H = - 1428 KJ. If the molar heats of formation of water and carbon (IV) oxide are - 286 kJ and - 396 kJ respectively, calculate the molar heat of formation of ethene in KJ

A. - 2792
B. + 2792
C. - 64
D. + 64

Question 38 :

• JAMB 1989

Gunpower is made from charcoal, sulphur and potassium trioxonitrate (V) The salt in the mixture performs the function of

A. An oxidant
B. A reductant
C. A solvent
D. A catalyst

Question 39 :

• JAMB 1990

Cr₂O₇ + 6Fe²⁺ + 14H⁺ → 2Cr³⁺ +6Fe³⁺ + 7H₂O. In the above , the oxidation number of chromium changed from?

A. +7 to +3
B. +6 to +3
C. +5 to +3
D. -2 to +3

Question 40 :

• JAMB 1990

In the reaction 1O^-₃ + 5l^- + 6H⁺ → 31₂ + 3H₂O, the oxidizing agent is?

A. H⁺
B. L^-
C. 1O^-
D. L₂