Name the gas that can readily decolourise acidified KMnO₄ solution.

(1) CO₂           

(2) SO₂           

(3) NO₂             

(4) P₂O₅

HgCl₂ and I₂ both when dissolved in water containing I^- ions the pair of species formed is

(a) HgI₂, ${\mathrm{I}}_3^{-}$                              (b) HgI₂, I^-

(c) ${\mathrm{HgI}}_4^{2-}, {\mathrm{I}}_3^{-}$                             (d) Hg₂I₂, I^-

The incorrect statement regarding the lanthanons is ;

Which one of the following statements is correct when SO₂ is passed through acidified

K₂Cr₂O₇ solution?

1. The solution is decolourized

2. SO₂ is reduced

3. Green Cr₂(SO₄)₃ is formed

4. The solution turns blue

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

1. [Xe]4f⁸6d²                   

2. [Xe]4f⁹5s¹

3. [Xe]4f⁷5d¹6s²                   

4. [Xe]4f⁶5d²6s²

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 reason for lanthanoid contraction is:

1. Negligible screening effect of 'f' orbitals

2. Increasing nuclear charge

3. Decreasing nuclear charge

4. Decreasing screening effect

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⁺

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