Oxidation and reduction - Jamb Chemistry Past Questions and Answers

Question 56:

• JAMB 1997

If 30cm³ of oxygen diffuses through porous plug in 7s, how long will it take 60 cm³ of chlorine to diffuse through the same plug?

A. 12s
B. 14s
C. 21s
D. 30s

Question 57:

• JAMB 1997

What is the oxidation number of Z in K₃ZCl₆?

A. -3
B. +3
C. -6
D. +6

Question 58:

• JAMB 1997

2H₂S_(g) + SO_2(g) + H₂O_(I) → 3S_(s) + 3H₂O_(I)..........(i) 3CuO_(s) + 2NH_3(g) → 3Cu_(s) + 3H₂O_(I) + N_2(g).........(II) In the equations above, the oxidizing agent (I) and the reducing agent in (II) respectively are?

A. H₂S _{and NH[sub]3}[/sub]
B. SO₂ and CuO
C. SO₂ and NH₃
D. H₂S _{and CuO}

Question 59:

• JAMB 1999

The correct order of increasing oxidation number of the transition metal ions for the compounds K₂Cr₂O₇, V₂O₅ and KMnO₄ is

A. V₂O₅ < K₂Cr₂O₇ < KMnO₄
B. K₂Cr₂O₇ < KMnO₄ < V₂O₅
C. KMnO₄ < K₂Cr₂O₇ < V₂O₅
D. KMnO₄ < V₂O₅ < K₂Cr₂O₇

Question 60:

• JAMB 2000

MnO_4(aq) + 8H⁺_(aq) + Y → Mn²⁺_(aq) + 4H₂O_(l)
Y in the equation above represents

A. 2e^-
B. 3e^-
C. 5e^-
D. 7e^-