[3 Mark Question Answer]

Question 13 Marks

Give two applications of chromatography.

Answer

Important applications of chromatography are given below:
$(i)$ It is used to separate solutions of coloured substances$($dyes and pigments$)$.
$(ii)$ It is used in forensic science to detect and identify trace amounts of substances $($like poisons$)$ in the contents of bladder or stomach.
$(iii)$ It is used to separate small amounts of products of chemical reactions.

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Question 23 Marks

What are the advantages of chromatography?

Answer

$1.$ A very small quantity of the substance can be separated.
$2.$ Components with very similar physical and chemical properties can be separated.
$3.$ It identifies the different constitutes of a mixture.
$4.$ It also helps in quantitive estimation of components of a mixture.

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Question 33 Marks

What is chromatography? For which type of mixture is it used?

Answer

This is one of the latest techniques to separate the coloured components of a mixture when all the components are very similar in their properties. Example: Components of ink are separated by this method. Ink is a mixture of different dyes, which are separated by chromatography because some of the dyes are less soluble and some are more soluble in a solvent.

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Question 43 Marks

Define mixture.

Answer

“Mixtures can be defined as. a kind of matter which is formed by mixing two or more pure substances $($elements and compounds$)$ in any proportion, such that they do not undergo any chemical change and retain their individual properties. Therefore they are impure substances.

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Question 53 Marks

Suggest a suitable technique to separate the constituents of the following mixtures. Also give the reason for selecting the particular method. Calcium carbonate and sodium chloride

Answer

Technique used is Solvent Extraction Method: Because, by this method, salts get dissolve in water while calcium carbonate being insoluble in water settles down in the container. And hence get separated about.

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Question 63 Marks

Suggest a suitable technique to separate the constituents of the following mixtures. Also give the reason for selecting the particular method. Sodium chloride and potassium nitrate

Answer

Technique used is Fractional$-$crystallisation.
Because: This method is used when solubility of solid components of mixture and different in the same solvent. Here, sodium chloride and potassium nitrate. Both are soluble in water but solubility of potassium nitrate is more.

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Question 73 Marks

Suggest a suitable technique to separate the constituents of the following mixtures. Also give the reason for selecting the particular method. Water and alcohol

Answer

Technique used to separate water and Alcohol is Fractional Distillation.
Because in this method, the vapours of water is left behind in the original vessel as the alcohol boils at lower temperature than water. Thus these two liquids can be separated.

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Question 83 Marks

Suggest a suitable technique to separate the constituents of the following mixtures. Also give the reason for selecting the particular method : on from sulphur

Answer

Technique to separate iron from sulpher is magnetic separation.
Because, this method is used when one of the component of mixture is Iron. Iron gets attracted towards the magnet and hence get separated.

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Question 93 Marks

Suggest a suitable technique to separate the constituents of the following mixtures. Also give the reason for selecting the particular method. Ammonium chloride from sand

Answer

Technique used to separate Ammonium chloride from sand is sublimation.
Because this method is used for solid mixtures in which one of the components can sublime on heating. In this method, Ammonium chloride changes into vapours on heating and salt is left behind.

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Question 103 Marks

Differentiate between: Homogenous and heterogenous substances

Answer

Homogeneous mixture $—$ is a mixture where the components that make up the mixture are uniformly distributed throughout the mixture.
Example $—$ air, sugar water, rain water.
Heterogeneous mixture $—$ is a mixture, where the components of the mixture are not uniform or have localized regios with different properties.
Example $—$ Cereal in milk, vegetable soup.

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