Subject

Chemistry

Class

CBSE Class 12

Pre Boards

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Sample Papers

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 Multiple Choice QuestionsShort Answer Type

1. Zn2+ salts are white while Cu2+ salts are coloured. Why?
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2.

How much charge is required for the reduction of 1 mol of Zn2+ to Zn?

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3.

Write the dispersed phase and dispersion medium of butter.

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4.

Write the structures of the following molecules:
(i) H2SO3
(ii) XeOF4

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5. Write down the IUPAC name of the complex [Pt(en)2Cl2]2+. What type of isomerism is shown by this complex?
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6.

 Using IUPAC norms write the formulate for the following coordination compounds:

(i) Hexaamminecobalt (III) chloride
(ii) Potassium tetrachloridonickelate (II)

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7.

Define rate of reaction? Write two factors that affect the rate of reaction.

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8.

Arrange the following in increasing order of their basic strength:

 

(i) C6H5 – NH2, C6H5 – CH2 – NH2, C6H5 – NH – CH3

 

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9.

Why does a solution containing non-volatile solute have higher boiling point than the pure solvent? Why is elevation of boiling point a colligative property?


The boiling point of substance can be defined as, it is the temperature at which the vapour pressure of the substance equal to atmospheric pressure. According to Raoult's law, the vapour pressure of a solvent decreases in the presence of a non-volatile solute. Thus, the vapour pressure of a solution containing a non-volatile solute requires a high temperature to become equal to the atmospheric pressure. That is why the boiling point of a solution containing a non-volatile solute increases. Thus, the solution containing a non-volatile solute has a higher boiling point than a pure solvent. Example of non-volatile solute sugar, NaCl. etc. 
Elevation in boiling point is a colligative property, as it depends on the number of solute particles present in a solution.

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10.

(i) What is the principle behind the zone refining of metals?

(ii) What is the role of silica in the extraction of copper?

(iii) How is 'cast iron' different from 'pig iron'?

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