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

Assuming complete ionisation, same moles of which of the following compounds will require the least amount of acidified KMnO₄ for complete oxidation?

• FeSO₄

• FeSO₃

• FeC₂O₄

• FeC₂O₄

Which of the statements given below is incorrect?

• Cl₂O₇ is an anhydride of perchloric acid

• O₃molecule is bent

• ONF is isoelectronic with NO₂

• ONF is isoelectronic with NO₂

Which one of the following compounds is a peroxide? 

• KO₂

• BaO₂

• MnO₂

• MnO₂

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

• La³⁺ (Z = 57)

• Ti³⁺ (Z = 22)

• Lu³⁺

• Lu³⁺

219.

Which of the following oxidation states is the most common among the lanthanoids

• 4

• 2

• 5

• 5

The Number of moles of KMnO₄  that will be needed to react with one mole of sulphite ion in acidic solution is:

• 3/5

• 4/5

• 2/5

• 1