Oxidation and Reduction

Q. State which substance is getting oxidised and reduced in the following equation:
MnO₂ + 4HCl -> MnCl₂ + 2H₂O + Cl₂

Q.

When hydrogen gas (H₂) is passed over copper oxide (CuO), copper (Cu) is produced along with water (H₂O). The balanced chemical equation for the given reaction is

Which substance is oxidized in the given reaction?

1. Cu

2. H₂

3. H₂O

4. CuO

Q.

The compound which cannot act as both oxidising and reducing agent is

1. $S{O}_2$

2. $A{l}_2{0}_3$

3. $Mn{O}_2$

4. CrO

Q.

Give two example from everyday life situations where redox reactions are taking place. [2 MARKS]

Q.

Why would fluorine have a positive oxidation state in "HOF" even though it is more electronegative?

Q.

Give two examples each of soluble salts and insoluble salts.

Q. The gain of electrons is known as and the loss of electrons is known as .

1. electrolysis
2. reduction
3. oxidation
4. decomposition

Q.

Question 38

A silver article generally turns black when kept in the open for a few days. The article when rubbed with toothpaste again starts shining.

(a) Why do silver articles turn black when kept in the open for a few days? Name the phenomenon involved.

(b) Name the black substance formed and give its chemical formula.

Q. ${\text{CO}}_2\text{(g)}+{\text{H}}_2\text{(g)}\to \text{CO(g)}+{\text{H}}_2\text{O(l)}$

The given reaction is an example of:

1. combination reaction
2. precipitation reaction
3. redox reaction
4. decomposition reaction

Q.

The general equation for the combustion of ammonia is :

1. NH₃ (g) +O₂ (g) → N₂ (g) + H₂O (g)

2. NH₃ (g) + O₂ (g) → N₂O (g) + H₂O (g)

3. NH₃ (g)+O₂ (g)→ NO₂ (g)+H₂O (g)

4. NH₃ (g) + O₂ (g) → NO (g) + H₂O (g)

Q. Hydrogen is manufactured by ‘Bosch process’.​
Give the equations with conditions.​

Q.

Which of the following is an example of redox reaction?

1. Burning of fuel

2. Corrosion of metal

3. Manufacture of NaOH

4. Respiration Reaction

Q.

“Reducing agents are electron acceptors”. Is the statement true or false?

1. True
2. False

Q.

The black coating on silver is due to _______ .

1. Decomposition reaction

2. none of these

3. Displacement reaction

4. Corrosion

Q.

Double displacement reaction is also known as partner exchange reaction.

1. True
2. False

Q.

How many electrons are lost by zinc during the process of oxidation?

1. 1

2. 2

3. 3

4. 4

Q.

Reduction is the process in which an atom (or ion) donates an electron or hydrogen ion reducing its oxidation number.

1. True

2. False

Q. Name​
(b) a nitrate which produces oxygen as the only gas.​

Q. What do you understand about a precipitation reaction? Explain with an example.

Q.

Zinc carbonate on heating forms zinc oxide and carbon dioxide. Tick the observations that indicate a chemical reaction has taken place.​

${\text{ZnCO}}_3\text{(s)}\to {\text{ZnO(s) + CO}}_2\text{(g)}$​

1. Colour change​
2. Change of odour​
3. Evolution of gas​
4. Formation of precipitate​

Q.

Identify the following reaction as either oxidation or reduction:

$\mathrm{K}-{\mathrm{e}}^{-}\to {\mathrm{K}}^{+}$

Q. Which among the following statements is correct for the given redox reaction:

${\text{Pb}}_3{\text{O}}_4+8\text{HCl}\stackrel{\text{Heat}}{\to }3{\text{PbCl}}_2+{\text{Cl}}_2+4{\text{H}}_2\text{O}$

1. I only
2. II only
3. I & III
4. II & IV

Q.

Redox reactions include :

1. Oxidation

2. Reduction

3. Transfer of electrons

4. None of these

Q.

Identify the following reactions as oxidation or reduction reaction:
i) $K-e^{-}\to K^{+}$
ii) $F{e}^{3+}+e^{-}\to F{e}^{2+}$

1. (i) Oxidation reaction
   (ii) Reduction reaction.

2. (i) Reduction reaction
   (ii) Oxidation reaction.

3. (i) Oxidation reaction
   (ii) Oxidation reaction.

4. (i) Reduction reaction
   (ii) Reduction reaction.

Q.

The atomic number of four elements A, B, C and D are given below.
Select the option that can act as a reducing agent for all the other options in a reaction.

A - 11, B - 15, C - 8 and D - 9

1. Element C

2. Element D

3. Element A

4. Element B

Q.

What is the process called when there is the gain in electron or hydrate ion or loss of oxygen in element?

1. Redox
2. Oxidation
3. Electronegativity
4. Reduction

Q. Identify the examples of combination reaction from the options given below.

1. $3{\text{Pb(NO}}_3{)}_2\text{(aq)}+2{\text{AlCl}}_3\text{(aq)}$ $\to$ $3{\text{PbCl}}_2\text{(s)}\downarrow +2\text{Al}{\text{(NO}}_3{)}_3\text{(aq)}$
2. $\text{Fe(s)}+{\text{CuSO}}_4\text{(aq)}\to {\text{FeSO}}_4\text{(aq)}+\text{Cu(s)}$
3. $\text{MgO(s)}+{\text{CO}}_2\text{(g)}\to {\text{MgCO}}_3\text{(s)}$
4. $8\text{Fe(s)}+{\text{S}}_8\text{(s)}\to 8\text{FeS(s)}$

Q.

What do you understand by the term Redox reaction?

Q. Which of the following is correct about the oxidation in the given equation?

$Zn\left(s\right)+2HCl\left(aq\right)\to ZnC{l}_2\left(aq\right)+H_2\left(g\right)$

1. Zinc is oxidized
2. Chlorine is oxidized
3. Hydrogen is oxidized
4. Zinc is reduced

Q.

When electric current is passed through a cell having an electrolyte, the positive ions move towards the cathode and the negative ions towards the anode. If the cathode is pulled out of the solution:

1. The positive ions will start moving towards the anode, the negative ions will stop moving

2. The negative ions will continue to move towards the anode and the positive ions will stop moving

3. The positive and negative ions will start moving randomly

4. The positive and negative ions will move towards the anode