Valency and Oxidation State

Q.

${\mathrm{H}}_2\mathrm{S}+{\mathrm{Cl}}_2\to \mathrm{S}+2\mathrm{HCl}$, which substance is: (1) Oxidised (2) Reduced. (3) The oxidising agent (4) The reducing agent. Give reasons?

Q. In the neutral or faintly alkaline medium, $KMn{O}_4$ oxidises iodide into iodate. The change in oxidation state of manganese in this reaction is from

Q.

How to find a oxidation number of the Coordinate compound?

Q.

What is the n-factor and how it is calculated for oxalic acid dihydrate?

Q.

n-factor of ${\mathrm{KMnO}}_4$ in neutral medium is:

1. 6

2. 5

3. 4

4. 3

Q.

Which of the statements about the reaction below are incorrect?

$2\mathrm{PbO}\left(\mathrm{s}\right)+\mathrm{C}\left(\mathrm{s}\right)\to 2\mathrm{Pb}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)$

(a) Lead is getting reduced (b) Carbon Dioxide is getting oxidized (c) Carbon is getting oxidized (d) Lead oxide is getting reduced

1. (a) and (b)

2. (a) and (c)

3. (a), (b) and (c)

4. all

Q.

Find the oxidation number of Carbon in Glucose ${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6$

Q. Assertion: The formal oxidation number of sulphur in $N{a}_2{S}_4{O}_6$ is 2.5.
Reason: Two $\text{S-atoms}$ are not directly linked via $\text{O-atoms}$.

1. Both Assertion and Reason are true but Reason is not the correct explanation for Assertion.
2. Both Assertion and Reason are true and Reason is the correct explanation for Assertion.
3. Both Assertion and Reason are false.
4. Assertion is true but Reason is false

Q. What will be the valence factor or n-factor $\left(n_f\right)$ for $H_{2}S{O}_4$ when
(i) It reacts with $NaOH$ to form $NaHS{O}_4$
(ii) It reacts with $NaOH$ to form $N{a}_{2}S{O}_4$

1. $n_f$ of $H_{2}S{O}_4$ is 2 for both the cases
2. (i) $n_f$ is $1$ and (ii) $n_f$ is $2$
3. $n_f$ of $H_{2}S{O}_4$ is 1 for both the cases
4. None of the above

Q.

What is the oxidation number of the sulfur atoms in ${\mathrm{Na}}_2{\mathrm{S}}_2{\mathrm{O}}_3$?

Q.

Which of the following oxide(s) of iron would be obtained on the prolonged reaction of iron with steam?

1. $\mathrm{FeO}$

2. ${\mathrm{Fe}}_2{\mathrm{O}}_3$

3. ${\mathrm{Fe}}_3{\mathrm{O}}_4$

4. ${\mathrm{Fe}}_2{\mathrm{O}}_3$ and ${\mathrm{Fe}}_3{\mathrm{O}}_4$

Q.

What is the oxidation number of oxygen in superoxides?

Q.

How to know whether the reaction is reduction or oxidation

Give me with an example

Q. In an experiment, 50 mL of 0.1 M solution of a salt reacted with 25 mL of 0.1 M solution of sodium sulphite. The half equation for the oxidation of sulphite ion is:
$S{O}_{3\left(aq\right)}^{2-}+H_{2}O\to S{O}_{4\left(aq\right)}^{2-}+2H_{\left(aq\right)}^{+}+2e^{-}$
If the oxidation number of the metal in the salt was 3, what would be the new oxidation number of the metal?

1. 0
2. 1
3. 2
4. 4

Q.

Is $2\mathrm{Na}+2{\mathrm{H}}_2\mathrm{O}\to 2\mathrm{NaOH}+{\mathrm{H}}_2$ a redox reaction?

Q.

The oxidation number of hydrogen is $+1$ except in_______.

Q.

The equivalent weight of aluminum in Al₂O₃ is:

Q. What is the oxidation number of chromium in K3[Cr(c2o4)].3h2o

Q.

A $100mL$ solution was made by adding $1.43g$ of ${\mathrm{Na}}_2{\mathrm{CO}}_3.{\mathrm{xH}}_2\mathrm{O}$.The normality of the solution is $0.1N$. The value of $x$ is ________. (The atomic mass of $Na$ is $23g/mol$).

Q. What will be the n-factor $\left(n_f\right)$ for $H_{3}P{O}_2$ and $H_{3}B{O}_3$ respectively?

1. $1,3$
2. $2,3$
3. $3,3$
4. $1,1$

Q.

What is the oxidation number of manganese $\left(\mathrm{Mn}\right)$ in potassium permanganate$\left({\mathrm{KMnO}}_4\right)$?

1. $+5$

2. $+7$

3. $+8$

4. $+9$

Q.

What is reduction? Give an example.

Q.

Describe the extraction of Sodium by electrolytic method through chemical equations.

Q. How much amount of $CaC{O}_3$ in grams having percentage purity $50$ percent produces $0.56$ $\text{L}$ of $C{O}_2$ at STP on heating?

1. $2.5\text{g}$
2. $7\text{g}$
3. $5\text{g}$
4. $3.5\text{g}$

Q.

In the formation of magnesium chloride (by direct combination between magnesium and chlorine), name the substance that is oxidized and the substance that is reduced.

Q. $13.4g$ of a sample of unstable hydrated salt, $N{a}_{2}S{O}_4.x{H}_{2}O$ was found to contain $6.3g\text{of}{H}_{2}O$. The number of molecules of water of crystallisation is:

1. $5$
2. $7$
3. $2$
4. $10$

Q.

In the reaction: $\mathrm{Zn}+{\mathrm{FeSO}}_4\to {\mathrm{ZnSO}}_4+\mathrm{Fe}$

1. $\mathrm{Zn}$ gets oxidized.

2. $\mathrm{Fe}$ gets oxidized.

3. $\mathrm{Zn}$ is an oxidizing agent.

4. $\mathrm{Zn}$ and $\mathrm{Fe}$ are both oxidized.

Q.

What is the n factor of boric acid?

Q. Calculate the total n-factor for the reduction half reaction given below:
$F{e}_2(S{O}_4{)}_3⟶FeO+S{O}_2$

1. 4
2. 5
3. 6
4. 8

Q.

$A20.0mL$ solution containing $0.2g$ impure $H_2{O}_2$ reacts completely with $0.316g$ of $KMn{O}_4$ in acid solution. The purity of $H_2{O}_2$ (in%) is (Nearest integer) $(\text{mol.wt.of}{H}_2{O}_2=34\text{mole.wt.of.KM}n{O}_4=158)$