KMnO₄ can be prepared from K₂MnO₄ as per reaction

$3{\mathrm{MnO}}_4^{2-} + 2{\mathrm{H}}_2\mathrm{O}\rightleftharpoons 2{\mathrm{MnO}}_4^{-} + {\mathrm{MnO}}_2 + 4{\mathrm{OH}}^{-}$

The reaction can go to completion by removing OH^- ions by adding

1. HCl

2. KOH

3. CO₂

4. SO₂

Among the following, the incorrect statement regarding interstitial compounds is:

1. They retain metallic conductivity.

2. They are chemically reactive.

3. They are much harder than the pure metal.

4. They have higher melting points than the pure metal.

Identify the mixture of metals that contain a non-metal as a constituent in it.

1. lnvar

2. Steel

3. Bell metal

4. Bronze

Acidified K₂Cr₂O₇ solution turns green when Na₂SO₃ is added to it. This is due to the

formation of

1. CrO^2-₄

2. Cr₂(SO₃)₃

3. CrSO₄

4. Cr₂(SO₄)₃

Which of the following ions will exhibit colour in aqueous solutions ?

1. La³⁺ (Z=57)

2. Ti³⁺ (Z=22)

3. Lu³⁺ (Z=71)

4. Sc³⁺ (Z=21)

Which of the following species is colourless?

1. ${\mathrm{TiF}}_6^{2-}$ and ${\mathrm{CoF}}_6^{3-}$ 

2. Cu₂Cl₂  and ${\mathrm{NiCl}}_4^{2-}$

3. ${\mathrm{TiF}}_6^{2-}$ and Cu₂Cl₂ 

4. ${\mathrm{CoF}}_6^{3-}$ and ${\mathrm{NiCl}}_4^{2-}$ 

identify the incorrect statement among the following:

(1) There is a decrease in the radii of the atoms or ions as one proceeds from La to Lu.

(2) Lanthanoid contraction is the accumulation of successive shrinkages

(3) As a result of lanthanoid contraction, the properties of 4d series of the transition elements have no similarities with the 5d series of elements

(4) Shielding power of 4f electrons is quite weak

In which of the following pairs are both the ions coloured in aqueous solution?

(1) Ni²⁺, Ti³⁺             

(2) Sc³⁺, Ti³⁺

(3) Sc³⁺, Co²⁺           

(4) Ni²⁺, Cu⁺

(At. no : Sc =21, Ti = 22, Ni = 28, Cu = 29, Co = 27)

Assuming complete ionisation, same moles of which of the following compounds will

require the least amount of acidified KMnO₄ for complete oxidation?

1. FeSO₄

2. FeSO₃

3. FeC₂O₄

4. Fe(NO₂)₂

The correct electronic configuration of Gadolinium(Atomic number = 64)  is :

1. [Xe]4f⁸6d²                   

2. [Xe]4f⁹5s¹

3. [Xe]4f⁷5d¹6s²                   

4. [Xe]4f⁶5d²6s²