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CBSE Class 12 Chemistry Solved Question Paper 2018

Short Answer Type

11.

Give reasons for the following:

Aquatic animals are more comfortable in the cold water than in warm water.

12.

Give reasons for the following:

Elevation of the boiling point of 1 M KCl solution is nearly double than that of 1 M sugar solution.

13.

Write the formula of the following coordination compound :
Iron(III) hexacyanoferrate (II)

14.

What type of isomerism is exhibited by the complex [Co(NH₃)₅ Cl]SO₄?

15.

Write the hybridisation and number of unpaired electrons in the complex [CoF₆]^3-.

Atomic No. of Co = 27

16.

Identify the chiral molecule in the following pair :

17.

Give reason:

E° value for a Mn³⁺/Mn²⁺ couple is much more positive than that for Fe3⁺/Fe²⁺.

18.

Give reason:

Iron has a higher enthalpy of atomization than that of copper.

19.
Sc³⁺ is colourless in aqueous solution whereas Ti³⁺ is coloured.

Electronic configuration of Ti³⁺ is [Ar]3d² 4s². Metal ions usually form hexacoordinated complexes with water molecules. According to Crystal field theory [Ti(H₂O)₆]⁺³, Ti³⁺ ion has outer shell configuration as $t_{2 g}^{1} e_{g}^{0}$ There is an electron free to jump between energy level. Thus Ti³⁺ ions selectively absorb certain colours, hence its solution is coloured.

SC³⁺, on the other hand, has an empty d orbital; the [Sc(H₂O)₆]⁺³ complex has no electrons in T₂g or e_g orbitals. Hence SC³⁺ is colourless in aqueous solution.