Look at the forward reaction:

Zn + Cu2+ Zn2+ + Cu

Which one of the following statement is TRUE?

1. Zn becomes reduced and Cu2+ becomes oxidized

2. Zn becomes reduced and Cu2+ becomes oxidized

3. Zn2+ becomes reduced and Cu becomes oxidized

4. Zn becomes oxidised and Cu2+ becomes reduced

5. Zn2+ becomes oxidized and Cu becomes reduced

Please choose one item from the list above

When heated with hydrogen, metallic sodium forms a substance called sodium hydride, Na+H-:

2Na + H2 2Na+H-.

The hydrogen behaves here as a/an

1. catalyst

2. oxidizing agent

3. reducing agent

4. base

5. acid

Please choose one item from the list above

Which one of the following half-reactions is an oxidation?

1. Ag+ + e- Ag

2. Co3+ + e- Co2+

3. Cl2(g) + 2e- 2Cl-

4. Ca Ca2+ + 2e-

5. Cu2+ + 2e- Cu

Please choose one item from the list above

Have a good look at the redox reaction shown below. What are the values of a, b and c which are required to balance it?

Cr2O72- + a H+ + 3 H2S b Cr3+ + 3 S + c H2O

1. a = 6, b = 2, c = 8

2. a = 5, b = 3, c = 2

3. a = 5, b = 4, c = 2

4. a = 7, b = 2, c = 5

5. a = 8, b = 2, c = 7

Please choose one item from the list above

Have a good look at the redox reaction shown below. What are the values of a, b and c which are required to balance it?

Cu + a SO42- + b H+ Cu2+ + c SO2 + 2H2O

1. a = 2, b = 1, c = 3

2. a = 1, b = 4, c = 1

3. a = 3, b = 2, c = 1

4. a = 1, b = 4, c = 2

5. a = 2, b = 3, c = 2

Please choose one item from the list above

Have a good look at the redox reaction shown below. What are the values of a, b and c which are required to balance it?

a MnO4- + b H2S + c H+ 2 Mn2+ + 5 S + 8 H2O

1. a = 5, b = 3, c = 2

2. a = 5, b = 4, c = 2

3. a = 6, b = 2, c = 8

4. a = 7, b = 2, c = 5

5. a = 2, b = 5, c = 6

Please choose one item from the list above