Is Matter Around Us Pure Test - 15

Chlorophyll consists of four pigments, which are chlorophyll a, chlorophyll b, caroteins, and xanthophylls. These pigments have specific affinities for specific surfaces and different solubilities in different solvents. They can easily be separated using paper chromatography.

The correct answer is D.

Why alternative A is wrong:

Pigments of chlorophyll cannot be separated using filtration as all the pigments are macromolecules, which cannot pass through a filter paper. Hence, this alternative is incorrect.

Why alternative B is wrong:

Evaporation will only remove the solvent, and all the pigments will remain. Therefore, various pigments of chlorophyll cannot be separated by evaporation. Hence, this alternative is incorrect.

Why alternative C is wrong:

Proteins binding chlorophyll can be separated by centrifugation, but various pigments of chlorophyll cannot be separated using the same method. Hence, this alternative is incorrect.

Sodium chloride is a compound. It contains sodium and chlorine as constituent elements in fixed proportions.

The correct answer is D.

Why alternative A is wrong:

Diet soda contains carbon dioxide and sugar in dissolved form. Hence, it is a mixture.

Why alternative B is wrong:

Salt dissolves in water to form salt solution, which is a mixture.

Why alternative C is wrong:

Though sand does not dissolve in water, it mixes with water to form a mixture.

Chalk is a chemical compound made up of calcium carbonate, CaCO₃. It is not a mixture of different compounds.

The correct answer is B.

Why alternative A is wrong:

Air is a mixture of several gases such as nitrogen, oxygen, carbon dioxide, water vapor etc.

Why alternative C is wrong:

Water is a chemical compound made up of hydrogen and oxygen.

Why alternative D is wrong:

Glucose is a chemical compound made up of carbon, hydrogen, and oxygen.

In a solution, the substance that is present in lesser amount is known as the solute, whereas the substance that is present in major quantity is known as the solvent. In the given solution, salt and sugar act as solute and water acts as solvent.

The correct answer is B.

When nitrogen and oxygen are taken in a container, they form a mixture. However, when this mixture is subjected to a very high temperature, nitrogen and oxygen chemically combine to form NO (nitric oxide) which is a compound.

Hence, the correct answer is option C

Compounds are formed when two or more elements are chemically combined. Water is a compound, which is formed when hydrogen and oxygen are chemically combined. Hence, water, hydrogen, and oxygen are correctly labelled in the table given in alternative C.

The correct answer is C.

A compound is a substance that has a definite chemical composition. Steel is made by adding carbon to iron. Some types of steel are also formed by adding magnesium and tungsten. Thus, the chemical formula of steel is not fixed. Therefore, it is an alloy, and not a compound. Hence, Christina incorrectly lists steel as a compound.

The correct answer is D.

Why alternative A is wrong:

Ethyl alcohol is a compound and has a definite chemical composition. Its molecular formula is C₂H₅OH.

Why alternative B is wrong:

Common salt is a compound. Its molecular formula is NaCl. The chemical composition of common salt is fixed and cannot be changed.

Why alternative C is wrong:

Water is a compound having a definite chemical composition. Its molecular formula is H₂O.

Water, in general, contains dissolved minerals and oxygen. When it is distilled, only water is obtained and even dissolved oxygen is removed from it. Hence, distilled water is not a solution. It is just a solvent.

The correct answer is A.

Why alternative B is wrong:

Skimmed milk is obtained when fats are removed from milk. Skimmed milk contains proteins and vitamins dissolved in water. Hence, skimmed milk is a solution.

Why alternative C is wrong:

Wine is obtained by fermentation of grapes, and contains alcohol dissolved in water. Hence, wine is a solution.

Why alternative D is wrong:

Ink is a solution containing either pigments or dyes dissolved in a solvent.

The density of DNA is different from other cellular constituents. Hence, it can be separated using centrifugation.

The correct answer is B.

Why alternative A is wrong:

Chromatography cannot be used to separate DNA from other cellular components as DNA is not soluble in most of the solvents. Hence, this alternative is incorrect.

Why alternative C is wrong:

Although density of DNA is more than that of other cellular components, it will not settle down, even if the components are kept for a very long time. Hence, sedimentation cannot be used to separate DNA from other cellular components. Hence, this alternative is incorrect.

Why alternative D is wrong:

Cells contain a lot of macromolecules and none of them can pass through a filter paper. Therefore, filtration cannot be used to separate DNA from other cellular components. Hence, this alternative is incorrect.

Bronze is an alloy of copper and tin. Hence, it is an example of a mixture.

The correct answer is A.

Why alternatives B, C and D are wrong:

Zinc, iron, and tin are all elements, and can be classified as metals. Hence, alternatives B, C, and D are incorrect.