Valency and Oxidation State

Q.

$2{\mathrm{H}}_2{\mathrm{O}}_2\to 2{\mathrm{H}}_2\mathrm{O}+{\mathrm{O}}_2$ is an example of a disproportionation reaction.

1. True
2. False

Q.

Write true or false. Correct the false statement.

Iron has only one valency

1. True
2. False

Q.

Name two elements with variable valency.

Q. Oxidation number of Fe in violet coloured complex $N{a}_4\left[Fe{\left(CN\right)}_5\left(NOS\right)\right]$ is :

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

Q. The oxidation number of N in $N_2{H}_5^{+}$

1. -1
2. 2
3. -3
4. -2

Q. In the reaction, $I_2+2S_2{O}_3^{2-}\to 2I^{-}+S_4{O}_6^{2-}$
equivalent weight of iodine is

1. 
2. 
3. 
4. 

Q.

Name the three elements which exhibit variable valency?

Q. The equivalent weight of $MnS{O}_4$ is half its molecular weight when it is converted to
(IIT-JEE, 1988)

1. $M{n}_2{O}_3$
2. $Mn{O}_4^{\ominus }$
3. $Mn{O}_4^{2-}$
4. $Mn{O}_2$

Q. Oxidation number of oxygen in $O_2$ molecule is

1. + 1
2. 0
3. - 2
4. + 2

Q. Which of the following cation is not hydrolyzed in aqueous solution?
(i)$M{g}^{2+}$ (ii)$C{a}^{2+}$ (iii)$N{a}^{+}$ (iv)$K^{+}$

1. (i), (ii)
2. (iii), (iv)
3. (i), (ii), (iii), (iv)
4. (i), (ii), (iii)

Q. When a sulphur atom becomes a sulphide ion

1. There is no change in the composition of atom
2. It gains two electrons
3. The mass number changes
4. None of these

Q. When an atom reacts chemically and gains one or more electrons, it is said to have been ?

1. Catalyzed
2. Oxidized
3. Reduced
4. Decomposed

Q.

Why do chemical properties along a period vary?

Q. In the reaction, $I_2+2N{a}_2{S}_2{O}_3\to 2NaI+N{a}_2{S}_4{O}_6$, equivalent weight of Iodine is:

1. $Molecularweight$
2. $\frac{Molecularweight}{2}$
3. $\frac{Molecularweight}{4}$
4. $\frac{Molecularweight}{3}$

Q. $\underset{–}{2CuS{O}_4}+4KI⟶{Cu}_2{I}_2+2K_{2}S{O}_4+I_2$
The equivalent weight of the underlined compound by taking its molecular weight as $M$ is :

1. $E=M$
2. $E=\frac{M}{2}$
3. none of these
4. $E=\frac{M}{3}$

Q. Which one of the following has the highest oxidation number of iodine

1. $K{I}_3$
2. $I{F}_5$
3. $KI{O}_4$
4. $KI$

Q. The sum of the oxidation numbers of all the carbons in $C_6{H}_{5}CHO$ is

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

Q. In the equation $H_{2}S+2HN{O}_3\to 2H_{2}O+2N{O}_2+S$ The equivalent weight of hydrogen sulphide is

1. 16
2. 34
3. 17
4. 68

Q.

why do you understand by valency of an atom?

Q. What is the difference between atomic mass and atomic mass number?

Q. The equivalent mass of$MnS{O}_4$ is half of its molecular mass when it is converted to:

1. $M{n}_2{O}_3$
2. $Mn{O}_2$
3. $Mn{O}_4^{-}$
4. $Mn{O}_4^{2-}$

Q. In the following reaction, $S{O}_2$ acts as a reducing agent $S{O}_2+C{l}_2+2H_{2}O\to H_{2}S{O}_4+2HCl$ . The equivalent weight of $S{O}_2$ will be

1. 64
2. 32
3. 16
4. 8

Q. $S{n}^{++}$ loses two electrons in a reaction. What will be the oxidation number of tin after the reaction

1. + 2
2. Zero
3. + 4
4. - 2

Q. What is the oxidation number of Ca in ${\mathrm{CaCl}}_2$?

Q. In which of the following compounds, is the oxidation number of iodine is fractional

1. $I{F}_3$
2. $I{F}_2$
3. $I{F}_7$
4. $I_3^{-}$

Q. What oxoacid of sulphur contains $S-S$ bond in its structure?

1. Disulphuric acid
2. Perdisulphuric acid
3. Hydrosulphurous acid
4. Disulphurous acid