Which one of the following statements is correct when SO₂ is passed through acidified K₂Cr₂O₇ solution?

• The solution is decolourized

• SO₂ is reduced

• Green Cr₂(SO₄)₃ is formed

• The solution turns blue

Because of lanthanoid contraction, of elements which of the following elements have nearly same atomic radii ? (Number in the parenthesis are atomic number).

• Ti (22) and Zr(40)

• Zr(40) and Nb (41)

• Zr (40) and Hf (72)

• Zr (40) and Hf (72)

In acidic medium,H₂O₂ changes Cr₂O₇^2- to CrO₅ which has two (-O-O-) bonds. Oxidation state of Cr in CrO₃ is 

• +5

• +3

• +6

• +6

Reason of lanthanoid contraction is

• negligible Screening effect of 'f' orbitals

• increasing the nuclear charge

• decreasing the nuclear charge

• decreasing the nuclear charge

Which of the following does not give oxygen on heating?

• KClO₃

• Zn(ClO₃)₂

• K₂Cr₂O₇

• K₂Cr₂O₇

Which of the following lanthanoid ions is diamagnetic?
(At. number; Ce =58, Sm =62, Eu =63, Yb = 70)

• Ce²⁺

• Sm²⁺

• Eu²⁺

• Eu²⁺

KMnO₄ can be prepared from K₂MnO₄ as per reaction

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

• HCl

• KOH

• CO₂

• CO₂

Which one of the following does not correctly represent the correct order of the property indicated aginst it? 

• Ti < V<Cr< Mn: increasing number of oxidation states

• Ti< V<Cr³⁺<Mn³⁺ : increasing magnetic moment

• Ti < V < Cr < Mn : Increasing melting points

• Ti < V < Cr < Mn : Increasing melting points

209.

Four successive members of the first series of the transition metals are listed below. For which one of them, the standard potential value has a positive sign?

• Co (Z=27)

• Ni (Z=28)

• Cu (Z=29)

• Cu (Z=29)

The catalytic activity of transition metals and their compounds is ascribed mainly to

• their magnetic behaviour

• their unfilled d- orbitals

• their ability to adopt variable oxidation states

• their ability to adopt variable oxidation states