In a mildly alkaline medium, thiosulphate ion is oxidized by ${\mathrm{MnO}}_4^{-}$ to "A". The oxidation state of sulphur in "A" is:

1.	+4	2.	+2
3.	–2	4.	+6

In basic medium CrO₄²⁻ oxidizes S₂O₃^2– to form S₂O₃²⁻  to form  SO₄²⁻  and itself changes into Cr(OH)₄⁻ . The volume of 0.154 M  CrO₄²⁻ required to react with 40 mL of 0.25 M S₂O₃²⁻ is: 

(Rounded-off to the nearest integer)

1. 178 
2. 173 
3. 169 
4. 181

The correct order of E^o_M²⁺/M values with a negative sign for the four successive elements Cr, Mn, Fe, and Co is:

1. Cr > Mn > Fe > Co

2. Mn > Cr > Fe > Co

3. Cr > Fe > Mn > Co

4. Fe > Mn > Cr > Co

In context with the transition elements, which of the following statements is incorrect?

A larger number of oxidation states are exhibited by the actinoids than by the lanthanoids, the main reason being:

1. More reactive nature of the actinoids than the lanthanoids

2. More energy difference between 5f and 6d than between 4f and 5d orbitals

3. Lesser energy difference between 5f and 6d than between 4f and 5d orbitals

4. 4f orbitals more diffuse than the 5f orbitals

If dichromate ion is treated with base, the oxidation number of Cr in the product formed will be:

1. +6

2. +4

3. +5

4. +2

Which of the following lanthanoids do not form MO₂ [where M is a lanthanoid metal]?

1. Pr

2. Dy

3. Nd

4. Yb

On treating a compound with warm dil. H₂SO₄, gas X is evolved
which turns K₂Cr₂O₇ paper acidified with dil. H₂SO₄ to a green compound Y.
Determine X and Y respectively:

1. $\mathrm{X}={\mathrm{SO}}_2,\mathrm{Y}={\mathrm{Cr}}_2{\mathrm{O}}_3$

2. $\mathrm{X}={\mathrm{SO}}_3,\mathrm{Y}={\mathrm{Cr}}_2{\mathrm{O}}_3$

3. $\mathrm{X}={\mathrm{SO}}_2,\mathrm{Y}={\mathrm{Cr}}_2{\left({\mathrm{SO}}_4\right)}_3$

4. $\mathrm{X}={\mathrm{SO}}_3,\mathrm{Y}={\mathrm{Cr}}_2{\left({\mathrm{SO}}_4\right)}_3$

Given below are two statements:

Statement I: CeO₂ can be used for the oxidation of aldehydes and ketones.

Statement II: Aqueous solution of EuSO₄ is a strong reducing agent.

In the light of the above statements, choose the correct answer from the options given below:

1. Statement I is false but statement II is true

2. Statement I is true but statement II is false

3. Both statement I and statement II are true

4. Both statement I and statement II are false