Subject

Chemistry

Class

ICSE Class 12

Pre Boards

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Sample Papers

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 Multiple Choice QuestionsShort Answer Type

31.

Write balanced equations for each of the following reactions :    

(i) Dilute hydrochloric acid is added to sodium thiosulphate solution.

(ii) Sodium hydroxide solution is added to silver nitrate solution

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32.

 Explain the following with at least one example :    

(i) Keto-enol tautomerism.

(ii) Carbylamine reaction.

(iii) Rosenmund’s reduction.

(iv) Haloform reaction.

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33.

 Give one reason each for the following :  

(i) Acetone reacts with hydroxylamine to form only one product which has no geometrical isomer, but acetaldehyde reacts with hydroxylamine to form a product which has two geometrical isomers.

(ii) Direct nitration of aniline is not possible.

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34.

Write balanced equations for the preparation of:  

(i) DDT

(ii) Urotropine

(iii) Biuret

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35.

Give balanced equations for the reactions given below:    

(i) Urea is warmed with a dilute solution of sodium hydroxide.

(ii) Methyl isocyanide is warmed with dilute hydrochloric acid.

(iii) Sucrose is warmed with concentrated nitric acid.

(iv) Aniline is treated with a mixture of NaNO2 and excess ofHCl at low temperature.

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36.

 How would you convert the following :

(i) Methyl amine to ethyl amine

(ii) Benzoic acid to benzene

(iii) Glucose to fructose

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37.

Give a chemical test to distinguish between : 

(i) Urea and oxalic acid

(iiAcetaldehyde and acetone.

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38.

i) What is a specific rotation ?   

(ii) 1. What is optical activity ?

2. Name the apparatus used to measure optical activity.

3. State the two necessary conditions for a compound to show optical activity. Give one example of a compound which shows optical activity.


(i) Specific rotation is the numbered of observed degree of rotation caused by an optically active substance when plane polarised light is passed through one decimetre of its solution having concentration one gram per millilitre.

(ii) 1. The property by which a substance rotates plane polarised light through a definite angle is called optical activity.

2. Optical activity is measured by polarimeter.

3. The two necessary conditions for the compound to show optical activity are.

(i) The compound must have at least one asymmetric or chiral carbon atom.

(ii) The compound must not have either a plane of symmetry or centre of symmetry. Lactic acid is an example of optically active compound.

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39. Give the name and formula of each A, B,C, D, E and F in the following conversion reactions :  

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40. What are polyolefins ? Give the reaction for the preparation of polythene a polyolefin. 
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