Oxidation and Reduction

Q. Give reason :​
(b) Aluminium is used in making aircraft.​

Q. An ___ is a substance that tends to bring about oxidation by being reduced.

1. 
2. 
3. All of these
4. 

Q.

Which of the following is reduction?

1. Fe²⁺ → Fe³⁺ + e^-

2. Hg²⁺ + 2^e- → Zn

3. Zn²⁺ + 2^e- → Zn

4. MnO₄^2- → MnO₄^- + e^-

Q.

Reduction involves :

1. Addition of Hydrogen

2. Addition of any electropositive element

3. Removal of oxygen

4. Removal of any electronegative element

Q. Which of the following is not true about redox reactions?

1. The substance that gets reduced is called the reducing agent.
2. In a redox reaction, oxidation and reduction happen simultaneously.
3. The substance that gets oxidized is called the reducing agent.
4. In a redox reaction, only reduction happens.

Q.

Reduction is the process in which an atom or group of atoms loses one or more electron

1. True

2. False

Q.

Oxidation involves :

1. Addition of oxygen

2. Removal of Hydrogen

3. Removal of Hydrogen electrons

4. Addition of any electronegative element

Q.

Fill in the blanks

1. Pb is the symbol of ________ element.

2. Neon and argon have ________ valency.

3. The substances formed as a result of chemical reaction are caled ______.

4. A reaction in which an element breaks up to form two or more subsances is called ____.

Q.

In the chemical reaction $C{l}_2+H_{2}S⟶2HCl+S$, the oxidation number of sulphur changes from

1. 2 to 0

2. - 2 to 0

3. - 2 to - 1

4. 0 to 2

Q. In the redox reaction, $Na+1/2H_2\to NaH$, choose the correct statement.

1. $Na$ is oxidising agent
2. $H_2$ undergoes reduction
3. $H_2$ is reducing agent
4. $Na$ undergoes reduction

Q. why is zinc used in dry cells ? explain

Q. Identify the combination reaction(s) among the following:

1. $\text{MgO(s)}+{\text{CO}}_2\text{(g)}\to {\text{MgCO}}_3\text{(s)}$
2. $3{\text{Pb(NO}}_3{)}_2\text{(aq)}+2{\text{AlCl}}_3\text{(aq)}\to 3{\text{PbCl}}_2\text{(s)}+2{\text{Al(NO}}_3{)}_3\text{(aq)}$
3. $2{\text{C}}_8{\text{H}}_{18}\text{(s)}+\text{2}5{\text{O}}_2\text{(g)}\to 16{\text{CO}}_2\text{(g)}+18{\text{H}}_2\text{O(g)}$
4. $8\text{Fe(s)}+{\text{S}}_8\text{(s)}\to 8\text{FeS(s)}$

Q. $2{\mathrm{CO}}_2\left(g\right)+2H_2\left(g\right)\stackrel{}{\to }2\mathrm{CO}\left(g\right)+2H_{2}O\left(g\right)$
In this reaction gets oxidised and gets reduced.

1. ${\text{CO}}_2$
2. ${\text{H}}_2$
3. $\text{CO}$
4. ${\text{H}}_2\text{O}$

Q.

By giving at least one example state how oxidation and reduction take place simultaneously.

Q. Why low oxidation states are favoured when a complex compound has ligands capable of ?- acceptor character in addition to sigma bonding?( Like in Ni(CO)4 oxidation state is zero)

Q.

Match the following reactions:-

$\begin{array}{cccc}& \text{Reaction Names}& & \text{Reactions}\\ \text{i}& \text{Displacement reaction}& & {\text{A. CaO + O}}_2\to {\text{2Ca(OH)}}_2\\ \text{ii}& \text{Decomposition Reaction}& & {\text{B. Fe + Pb(NO}}_3{)}_2\to {\text{Fe(NO\_3)}}_2\text{+ Pb}\\ \text{iii}& \text{Redox Reaction}& & {\text{C. MgCl}}_2{\text{+ Ca(OH)}}_2\to {\text{Mg(OH)}}_2{\text{+ CaCl}}_2\\ \text{iv}& \text{Combination Reaction}& & {\text{D. KClO}}_3\to {\text{2KCl + 3O}}_2\\ \text{v}& \text{Double Displacement Reaction}& & {\text{E. CO}}_2{\text{+ H}}_2\to {\text{2CO + H}}_2\text{O}\end{array}$

1. i - B, ii - D, iii - E, iv - A and v - C

2. i - A, ii - E, iii - F, iv - B and v - C

3. i - A, ii - F, iii - E, iv - B and v - C

4. i - B, ii - E, iii - D, iv - A and v - C

Q.

Oxidation is the process in which an atom or a group of atoms taking part in a chemical reaction loses one or more electron.

1. False

2. True

Q.

Which of the given statements are correct about the reaction mentioned below?
$2Pb{O}_{\left(s\right)}+C_{\left(s\right)}\to 2P{b}_{\left(s\right)}+C{O}_{2\left(s\right)}$
i) Lead is getting reduced
ii) Carbon dioxide is getting oxidised
iii) Carbon is getting oxidised
iv) Lead oxide is getting reduced

1. (iii) and (iv)

2. (i) and (iii)

3. (i) and (ii)

4. (i), (ii) and (iii)

Q.

Select the combination reactions between: (i) elements, (ii) compounds and (iii) an element and a compound, for the given reaction.

$$\begin{gathered} 2\mathrm{CO}\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2{\mathrm{CO}}_2\left(\mathrm{g}\right) \\ (\mathrm{Carbon}(\mathrm{Oxygen})(\mathrm{Carbon}\mathrm{dioxide}) \\ \mathrm{monoxide}) \end{gathered}$$