Explain why:Transition elements usually form coloured ions. from

Subject

Chemistry

Class

ICSE Class 12

Pre Boards

Practice to excel and get familiar with the paper pattern and the type of questions. Check you answers with answer keys provided.

Sample Papers

Download the PDF Sample Papers Free for off line practice and view the Solutions online.
Advertisement

 Multiple Choice QuestionsShort Answer Type

31.

Give a reason for the following:

Gelatin is added to ice creams.


32.

For the complex ion [Fe(CN)6]3-, state:

(i) The type of hybridisation

(ii) The magnetic behaviour

(iii) The oxidation number of the central metal atom


33.

Write the IUPAC name of [Co(en)2Cl2]+ ion and draw the structure of its geometrical isomers.


34.

Explain why :

Mn2+ is more stable than Fe2+ towards oxidation to +3 state. (At. no. of Mn = 25, Fe = 26)


Advertisement
Advertisement

35.

Explain why:

Transition elements usually form coloured ions.


Transition element exhibit colour due to d-d transition, a d-d transition is possible only when d- subshell have an unpaired electron. Thus transition metal compounds are shows colour because of the presence of one or more unpaired electrons in the d-orbital of the metal ion. A compound of transition metal appears coloured when one frequency of definite energy is absorbed (△E = hv) for the d-d transition of the unpaired electron and other frequencies of the visible region are transmitted. The colour of the compound corresponds to the frequency of the transmitted light. Thus, the observed colour (frequency) is complementary to the absorbed frequency.


Advertisement
36.

Explain why:

Zr and Hf exhibit similar properties.


37.

Complete and balance the following chemical equations:(i) KMnO4 + KI + H2SO4   __+___+____+__(ii) K2Cr2O7 + H2SO4 + H2S   __ + ___+ ___+ __(iii) KMnO4 + H2SO4 + FeSO4   __ + ___+ ____ +__


38.

Arrange the following in the increasing order of their basic strength:

C2H5NH2, C6H5NH2, (C2H5)2NH


Advertisement
39.

Give a balanced chemical equation of convert methyl cyanide to ethyl alcohol.


40.

What happens when benzene diazonium chloride reacts with phenol in weak alkaline medium? (Give balanced equation).


Advertisement