Redox Reactions

Q.

What are oxidizing and reducing agents? Give examples.

Q.

${\mathrm{CH}}_4+2{\mathrm{O}}_2\stackrel{∆}{\to }{\mathrm{CO}}_2+2{\mathrm{H}}_2\mathrm{O}$ Is it a redox reaction?

If yes, give a reason.

Q.

Give an example of a compound which acts as both oxidising and reducing agents.

Q. What is the standard electrode potential for the electrode, $Mn{O}_4^{-}|Mn{O}_2$ in an acid solution?


$E_{Mn{O}_4^{-}/M{n}^{2+}}^0=1.51V{E}_{Mn{O}_2/M{n}^{2+}}^0=1.23V$

1. 
   $0.87V$
2. 
   $2.45V$
3. 
   $1.70V$
4. $3.35V$

Q. When an electric current is passed through acidulated water, $112\text{mL}$ of hydrogen gas at NTP collects at the cathode in $965\text{sec}$. The current passes, in ampere is

1. $0.1$
2. $0.5$
3. $1.0$
4. $2.0$

Q.

Fluorine reacts with ice and results in the change:
$H_{2}O\left(s\right)+F_2\left(g\right)\to HF\left(g\right)+HOF\left(g\right)$
Justify that this reaction is a redox reaction.

Q. How many moles of lead (II) chloride will be formed from a reaction between $6.5g$ of $PbO$ and $3.2g$ of $HCl$ ?

1. $0.011$
2. $0.029$
3. $0.044$
4. $0.333$

Q. In the reaction $4A+2B+3C\to A_4{B}_2{C}_3$
What will be the number of moles of product formed starting from $1\text{mol}$ of $A$, $0.6\text{mol}$ of $B$ and $0.72\text{mol}$ of $C$ ?

1. $0.25$
2. $0.3$
3. $0.24$
4. $2.32$

Q.

Hydrogen peroxide decomposes to form water and oxygen. The uncatalysed reaction has activation energy of 86 kJ/mol. The activation energy value in the presence of acetanilide is 112 kJ/mol and in the presence of MnO₂ it is 49 kJ/mol. What conclusion can you draw from the above observation ?

Q.

Justify that the following reactions are redox reactions:
$CuO\left(s\right)+H_2\left(g\right)\to Cu\left(s\right)+H_{2}O\left(g\right)$

$F{e}_2{O}_3\left(s\right)+3CO\left(g\right)\to 2Fe\left(s\right)+3C{O}_2\left(g\right)$

$4BC{l}_3\left(g\right)+3LiAl{H}_4\left(s\right)\to 2B_2{H}_6\left(g\right)+3LiCl\left(s\right)+3AlC{l}_3\left(s\right)$

$2K\left(s\right)+F_2\left(g\right)\to 2K+F–\left(s\right)$

$4N{H}_3\left(g\right)+5O_2\left(g\right)\to 4NO\left(g\right)+6H_{2}O\left(g\right)$

Q.

Which among the following changes are exothermic or endothermic in nature?

a) Decomposition of ferrous sulfate

b) Dilution of sulfuric acid

c) Dissolution of sodium hydroxide in water

d) Dissolution of ammonium chloride in water

Q. The spin-only magnetic moment value of the most basic oxide of vanadium among $V_2{O}_3,V_2{O}_{4}and{V}_2{O}_5$ is B.M. (Nearest integer)

Q.

Which of the following reaction is not a redox reaction?

1. (A) Combustion

2. (B) Double displacement

3. (C) Synthesis of two elements

4. (D) Decomposition into elements

Q. 5 ml of $0.1MPb(N{O}_3{)}_2$ is mixed with 10 ml of 0.02 M $KI$. The amount of $Pb{I}_2$ precipitated will be about:

1. ${10}^{-2}mol$
2. ${10}^{-4}mol$
3. $2\times {10}^{-4}mol$
4. ${10}^{-3}mol$

Q.

Name some devices that use a battery.

Q. Which of the following is a redox reaction?

1. $2Na\left[Ag\right(CN{)}_2]+Zn\to N{a}_2[Zn\left(CN{)}_4\right]+2Ag$
2. $Ba{O}_2+H_{2}S{O}_4\to BaS{O}_4+H_2{O}_2$
3. $N_2{O}_5+H_{2}O\to 2HN{O}_3$
4. $NaOH+HCl\to H_{2}O+NaCl$

Q.

Phenol is heated with a solution of a mixture of KBr and KBrO_3. The major product obtained in the above reaction is

1. 2, 4, 6-Tribromophenol

2. 3-Bromophenol

3. 2-Bromophenol

4. 4-Bromophenol

Q. Chromium metal can be plated out from an
acidic solution containing $Cr{O}_3$ according to the following reaction:
$Cr{O}_3+6H^{+}+6e^{-}\to Cr+3H_{2}O$
Calculate the mass (m) of chromium plated out by $24000coulomb$.
Also, find the time (t) it will take to plate out $1.5g$ of chromium using $12.5A$ current.
Current efficiency is $40\%$
Molecular weight of $Cr$ is $52gmo{l}^{-1}$

1. $m=8.44gt=26min$
2. $m=2.15gt=55.6min$
3. $m=8.44gt=12.41min$
4. $m=2.15gt=88.32min$

Q.

Chlorine is used to purify drinking water. Excess of chlorine is harmful. The excess of chlorine is removed by treating with sulphur dioxide. Present a balanced equation for this redox change taking place in water.

Q.

Which one of the following is the first popular artificial sweeteners?

1. Alitame

2. Saccharin

3. Sucrolose

4. aspartame

Q. The conversion of $Pb{O}_{2}toPb(N{O}_3{)}_2$ is

1. Reduction
2. Oxidation
3. Neither Oxidation nor reduction
4. Both oxidation & reduction

Q. When Preacts with caustic soda, the products are $P{H}_3$ and $Na{H}_{2}P{O}_2$. This reaction is an example of

1. Oxidation
2. Reduction
3. Oxidation and reduction (Redox)
4. Neutralization

Q.

What are amphoteric oxides? Give two examples of amphoteric oxides.

Q. The minimum quantity of $H_{2}S$ needed to precipitate $63.5g$ of $C{u}^{2+}$ will be nearly -

1. $34.0g$
2. $2.0g$
3. $63.5g$
4. $31.75g$

Q.

A gaseous oxide contains 30.4% of nitrogen, one molecule of which contains one nitrogen atom. The density of the oxide relative to oxygen is

1. 0.94

2. 1.44

3. 1.50

4. 3.0

Q. In the reaction of oxalate with permanganate in acidic medium, the number of electrons involved in producing one molecule of $C{O}_2$ is:

1. 1
2. 10
3. 2
4. 5

Q.

Stronger the oxidizing agent, greater is the:

1. Oxidation potential

2. Reactivity

3. Reduction potential

4. Ionic behaviour

Q. Which of the following is not a reducing agent?

1. $NaN{O}_2$
2. $NaN{O}_3$
3. $SnC{l}_2$
4. $H_2$

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

1. 0 to 2
2. 2 to 0
3. 2 to 0
4. -2 to -1

Q. Which one of the following reactions is a redox reaction?

1. $N{a}_{2}S{O}_4+BaC{l}_2\to BaS{O}_4+2NaCl$
2. $S{O}_2+H_{2}O\to H_{2}S{O}_3$
3. $2CuS{O}_4+4KI\to C{u}_2{I}_2+2K_{2}S{O}_4+I_2$
4. $CuS{O}_4+4N{H}_3\to \left[Cu\right(N{H}_3{)}_4]S{O}_4$