OXIDATION AND REDUCTION

The oxidation number of sulphur in the S₂O₃^2- ion is

• +2

• +4

• +6

• +8

The oxidation state of Br in BrO₃^- ion is

• 1+

• 2+

• 3+

• 5+

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Consider the following M(s) --> M²⁺ (aq) In the reaction represented above, metal M: i. has been oxidised

ii. has increased in oxidation number

iii. has gained electrons

• i only

• i and ii only

• ii and iii only

• 1, ii, and iii

Tags

NGSS.HS-PS1-2

Which of the following is true about a reducing agent?

• It causes an increase in oxidation number

• It causes a loss of electrons

• Its oxidation number increases

• It gains electrons

Tags

NGSS.HS-PS1-2

In which of the following reactions does the oxidation number of nitrogen show the greatest increase?

• 2 NO(g) + O_{2 (g)} -->

  2 NO_{2 (g)}

• 4NO₂(g) + O₂(g) + 2H₂O(l) --> 4 HNO₃ (aq)

• N₂ (g) + 3 H₂ --> 2NH₃(g)

• 2NH₃(g) + 3CuO (S) --> N₂(g) + 3 Cu (s) + 3H₂O (l)

Tags

NGSS.HS-PS1-2

Which of the following reactions is not a redox reaction?

• 2Na (s) + 2H₂O(l) ----> 2 NaOH (aq) + H₂(g)

• Fe (s) + 2HCl (aq) ----> FeCl₂(aq) + H₂(g)

• MgO(s) + H₂SO₄ (aq) --> MgSO₄(aq) + H₂O(l)

• C(s) + O2(g) --> CO2(g)

Tags

NGSS.HS-PS1-2

In the following reaction Cu (s) + 4HNO₃ (aq) ---> Cu(NO₃)₂(aq) + 2NO₂(g) + 2 H₂O(l)

Which of the following statement about copper is true?

• Copper undergoes reduction and its oxidation number decreases

• copper undergoes oxidation and its oxidation number increases

• Copper undergoes reduction and its oxidation number increases

• Copper undergoes oxidation and its oxidation number increases

Tags

NGSS.HS-PS1-2

In separated experiments, sulphur dioxide was bubbled into acidified solutions of potassium dichromate (vi) . Which of the following pairs correctly describes the colour changes observed in the experiment?

• colour of potassium dichromate (vI) changes from orange to green and the colour of potassium manganate (vii) from colourless to purple

• colour of potassium dichromate (vI) changes from orange to green and the colour of potassium manganate (vii) from purple to colourless

• colour of potassium dichromate (vI) changes from green to orange and the colour of potassium manganate (vii) from colourless to purple

• colour of potassium dichromate (vI) changes from green to orange and the colour of potassium manganate (vii) from purple to colourless

Tags

NGSS.HS-PS1-2

When acidified hydrogen peroxide solution is added to iron (ii) sulphate solution

• A pale green solution is formed

• the iron(ii) ion is oxidised to the iron(iii) ion

• the oxidation number of the iron (ii) ion decreases

• the acidified hydrogen peroxide is acting as a reducing agent

Tags

NGSS.HS-PS1-2

The figure shwos the label on a multivitamin and mineral supplement bottle, Much of the information has been left out. State what you would expect to observe if a solution is made of one of the tablets and acidified hydrogen peroxide is added to the soluiton

• the solution will turn yellowish brown

• the solution will turn colourless

• There will be no change in the solution

• the solution will turn blue

Tags

NGSS.HS-PS1-2