Match Column I with Column II for the oxidation states of the central atoms.

	Column I		Column II
A.	${\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}$	1.	+3
B.	${\mathrm{MnO}}_4^{-}$	2.	+4
C.	${\mathrm{VO}}_3^{-}$	3.	+5
D.	${\mathrm{FeF}}_6^{3-}$	4.	+6
		5.	+7

Codes:

Options:	A	B	C	D
1.	4	5	3	1
2.	1	2	3	5
3.	5	4	3	2
4.	4	5	3	2

Match the items in Column I with relevant items in Column II.

Codes:

Given below are two statements: 

Arrange the given reduction potentials of some ions in decreasing order of oxidising power:

Which two changes occur in the oxidation number of chlorine when chlorine gas is passed through hot NaOH solution?

a. 0 to +5

b. 0 to +3

c. 0 to -1

d. 0 to +1

Choose the correct option:

1. (a, b)
2. (b, c)
3. (c, d)
4. (a, c)

In which of the following reactions conc. H₂SO₄ is used as an oxidising reagent?

Choose the correct option:

Which of the following arrangements represents the increasing oxidation number of the central atom?

1. ${\mathrm{CrO}}_2^{-},$ ${\mathrm{ClO}}_3^{-},$ ${\mathrm{CrO}}_4^{2-},$ ${\mathrm{MnO}}_4^{-}$

2. ${\mathrm{ClO}}_3^{-},$ ${\mathrm{CrO}}_4^{2-},$ ${\mathrm{MnO}}_4^{-},$ ${\mathrm{CrO}}_2^{-}$

3. ${\mathrm{CrO}}_2^{-},$ ${\mathrm{ClO}}_3^{-},$ ${\mathrm{MnO}}_4^{-},$ ${\mathrm{CrO}}_4^{2-}$

4. ${\mathrm{CrO}}_4^{2-},$ ${\mathrm{MnO}}_4^{-},$ ${\mathrm{CrO}}_2^{-},$ ${\mathrm{ClO}}_3^{-}$

In which of the following compounds, an element exhibits two different oxidation state?

Which of the following statement regarding the rules to calculate the oxidation number is incorrect?