In the conversion ${\text{Br}}_2\mathrm{\hspace{0.17em}}\to \mathrm{\hspace{0.17em}}{\mathrm{BrO}}_3^{-},$ the oxidation state of bromine changes from -

(1) – 1 to – 1

(2) 0 to – 1

(3) 0 to + 5

(4) 0 to – 5

Oxidation number of cobalt in K[Co(CO)₄] is

(1) + 1

(2) + 3

(3) – 1

(4) – 3

The oxidation number of nickel in Ni(CO)₄

1. 0

2. + 4

3. – 4

4. + 2

Sn⁺⁺ loses two electrons in a reaction. The final oxidation number of tin will be:

1. + 2

2. Zero

3. + 4

4. – 2

The oxidation number of S in H₂S₂O₈ is:

1. + 2

2. + 4

3. + 6

4. + 7

The oxidation state of nitrogen in N₃H is:

1. $+\frac{1}{3}$

2. + 3

3. –1

4. $-\frac{1}{3}$

The oxidation state of Cr in [Cr(NH₃)₄Cl₂]⁺ is [AIEEE 2005]

(1) +3

(2) +2

(3) +1

(4) 0

A brown ring complex compound is formulated as $\left[Fe{\left(H_{2}O\right)}_{5}NO\right]S{O}_4.$ The oxidation state of iron is 

1. 1

2. 2

3. 3

4. 0

The oxidation number of P in Mg₂P₂O₇ is - 

What is the oxidation number of sulphur in $N{a}_2{S}_4{O}_6$ - 

(1) $\frac{2}{3}$

(2) $\frac{3}{2}$

(3) $\frac{3}{5}$

(4) $\frac{5}{2}$