Which of the statements is not true?

1. On passing H₂S through acidified K₂Cr₂O₇ solution, a milky colour is observed

2. Na₂Cr₂O₇ is preferred over K₂Cr₂O₇ in volumteric analysis

3. K₂Cr₂O₇ solution in acidic medium is orange

4. K₂Cr₂O₇ solution becomes yellow on increasing the pH beyond 7

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)

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)

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

1. lnvar

2. Steel

3. Bell metal

4. Bronze

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

A diamagnetic lanthanoid ion among the following is :

(At. numbers:  Ce = 58, Sm = 62, Eu = 63, Yb = 70)

1. Ce²⁺

2. Eu²⁺

3. Sm²⁺

4. Yb²⁺

The reason for lanthanoid contraction is:

1. Negligible screening effect of 'f' orbitals

2. Increasing nuclear charge

3. Decreasing nuclear charge

4. Decreasing screening effect

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

The incorrect statement regarding the lanthanons is ;