Question

The Orange colour of Cr₂O₇^2– ion changes to yellow when treated with an
alkali. Why ?

Solution

The Orange colour of Cr₂O₇^2– ion changes to yellow when treated with an
alkali because of the formation of chromate ion CrO₄^2- ion, which is yellow in colour.
$stack Cr subscript 2 straight O subscript 7 superscript 2 minus end superscript space with Orange below plus straight H subscript 2 straight O space rightwards harpoon over leftwards harpoon space stack Cr subscript 2 straight O subscript 4 superscript 2 minus end superscript with Yellow below space plus space 2 straight H to the power of plus$

Some More Questions From The d-And-f-Block Elements Chapter

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The D-And-f-Block Elements

The Orange colour of Cr₂O₇^2– ion changes to yellow when treated with an
alkali. Why ?

Some More Questions From The d-And-f-Block Elements Chapter

Explain why Cu⁺ ion is not stable in aqueous solutions?

Actinoid contraction is greater from element to element than lanthanoid contraction. Why?

On what ground can you say that scandium (Z = 21) is a transition element but zinc (Z = 30) is not?

The outer electronic configuration of copper is 3d¹⁰ 4s¹, yet it is considered transition element. Why?

Why the melting points of transition elements are high?

Why Zn, Cd and Hg are not regarded as transition elements?

Name the first element of 3rd transition series.

Though copper, silver and gold have completely filled sets of d-orbitals yet they are considered as transition metals. Why?

Why are transition elements so named?

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The D-And-f-Block Elements

The Orange colour of Cr2O72– ion changes to yellow when treated with analkali. Why ?

Some More Questions From The d-And-f-Block Elements Chapter

Explain why Cu+ ion is not stable in aqueous solutions?

Actinoid contraction is greater from element to element than lanthanoid contraction. Why?

On what ground can you say that scandium (Z = 21) is a transition element but zinc (Z = 30) is not?

The outer electronic configuration of copper is 3d10 4s1, yet it is considered transition element. Why?

Why the melting points of transition elements are high?

Why Zn, Cd and Hg are not regarded as transition elements?

Name the first element of 3rd transition series.

Though copper, silver and gold have completely filled sets of d-orbitals yet they are considered as transition metals. Why?

Why are transition elements so named?

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

The Orange colour of Cr₂O₇^2– ion changes to yellow when treated with an
alkali. Why ?

Explain why Cu⁺ ion is not stable in aqueous solutions?

The outer electronic configuration of copper is 3d¹⁰ 4s¹, yet it is considered transition element. Why?