Subject

Chemistry

Class

CBSE 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.
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 Multiple Choice QuestionsShort Answer Type

21.

Arrange the following compounds in an increasing order of their solubility in water: 

C6H5NH2, (C2H5)2NH, C2H5NH2
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22.

What are biodegradable polymers?

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23.

Explain the following giving one example for each: 

(i) Reimer-Tiemann reaction. 

(ii) Friedel Craft’s acetylation of anisole.

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24.

How would you obtain 

(i) Picric acid (2, 4, 6-trinitrophenol) from phenol, 

(ii) 2-Methylpropene from 2-methylpropanol? 

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25.

What is essentially the difference between α-form of glucose and β-form of glucose? Explain.

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26. Describe what you understand by the primary structure and secondary structure of proteins.


Primary structure of proteins: Each polypeptide chain in a protein has amino acids linked with each other in a specific sequence. This sequence of amino acids is said to be the primary structure of proteins.

2. The secondary structure of proteins: The secondary structure of proteins refers to the shape in which a long polypeptide can exist. The two different secondary structures possible are α-helix structure and β-pleated sheet structure.

(i) α-Helical structure: In α-Helix structure, a polypeptide chain forms all possible hydrogen bonds by twisting into a helix with -NH group of each amino acid residue and hydrogen bonded to >C=O of an adjacent turn of the helix. The structure can be drawn as follows.

(ii) β-pleated structure: In a β-pleated structure, all peptide chains are stretched out to nearly maximum extensions and then laid side by side which are held together by intermolecular hydrogen bonds.

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27.

Mention two important uses of each of the following:

 (i) Bakelite

 (ii) Nylon 6

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28.

 Explain why an alkylamine is more basic than ammonia.

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29.

How would you convert? 

(i) Aniline to nitrobenzene 

(ii) Aniline to iodobenzene

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 Multiple Choice QuestionsLong Answer Type

30.

(a) Differentiate between molarity and molality for a solution. How does a change in temperature influence their values? 

(b) Calculate the freezing point of an aqueous solution containing 10.50 g of MgBr2in 200 g of water. (Molar mass of MgBr2 = 184 g) (Kf for water = 1.86 K kg mol-1

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