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

575.

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

Which of the following exhibits only +3 oxidation states?

• U

• Th

• Ac

• Ac

For the four successive transition elements (Cr, Mn, Fe and Co), the stability of +2 oxidation state will be there in which of the following order?

(At. no. Cr = 24, Mn = 25, Fe = 26, Co = 27)

• Fe > Mn > Co> Cr 

• Co > Mn > Fe > Cr

• Cr > Mn > Co > Fe

• Cr > Mn > Co > Fe

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

• CrO₄^2-

• Cr₂(SO₃)₃

• CrSO₄

• CrSO₄

Gadolinium belongs to 4f series. Its atomic number is 64. which of the following is the correct electronic configuration of gadolinium?

• [Xe]4f⁸ 6d²

• [Xe]4f⁹5s¹

• [Xe]4f⁷ 5d¹6s²

• [Xe]4f⁷ 5d¹6s²