Subject

Chemistry

Class

CBSE Class 12

Pre Boards

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Sample Papers

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 Multiple Choice QuestionsShort Answer Type

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31.

When concentrated sulphuric acid was added to an unknown salt present in a test tube a brown gas (A) was involved. This gas intensified when copper turnings were added to this test tube. On cooling, the gas (A) changed into a colourless solid (B).
(i) Identify (A) and (B)
(ii) Write the structures of (A) and (B)
(iii) Why does gas (A) change to solid on cooling


(i) A is NO2 gas (because NO3- salt reacts with conc. H2SO4 to give NO2 gas which is brown). (B) is N2O4

(ii)

(iii) NO2 (A) is an odd electron-molecule. Thus, to become stable, it decreases to give N2O4 which is a colourless solid.


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32.

Arrange the following in the decreasing order of their reducing character:

HF, HCl, HBr, HI


33.

Complete the following reaction:
xeF4 + SbF5 -->


34.

Write the IUPAC name of the following:


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35.

Out of chlorobenzene and benzyl chloride, which one gets easily hydrolysed by aqueous NaOH and why?


36.

How do you convert the following?

Ethanal to Propanone


37.

How do you convert the following?

Toluene to Benzoic acid


38.

Aromatic carboxylic acids do not undergo Friedel-Crafts reaction.


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39.

pKa value of 4-nitrobenzoic acid is lower than that of benzoic acid.


40.

Write the structures of the main products in the following reaction:


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