Is Matter Around Us Pure Test - 17

The technique of centrifugation is applied to separate cream from milk. This technique is applied to separate the mixtures of solids and liquids in which the solid particles are so small that they cannot be separated by filtration.

In this process, the denser particles are forced to the bottom and the lighter particles stay at the top when spun rapidly.

The correct answer is B.

Metals are malleable, i.e., they can be hammered into thin sheets. Aluminium is a metal and can be beaten into thin sheets. Hence, it is malleable.

The correct answer is C.

Metals allow heat to flow from a hotter region to a colder region by the process of conduction. Hence, metals are good conductors of heat.

The correct answer is D.

A substance composed of two or more elements, chemically bonded together, in a fixed proportion is called a compound. Methane (CH₄) is a compound in which one carbon atom and four hydrogen atoms are chemically bonded together.

The correct answer is A.

A mixture is composed of two or more elements or compounds that do not have a fixed composition. It has a variable composition throughout. These elements or compounds just mix to form a mixture and the formation of new substances does not take place. The mixture shows the properties of constituent substances and these constituents can be separated by physical methods.

The correct answer is A.

A matter is said to be pure if it consists of a single type of particle and the constituent particles cannot be separated by any physical methods. Salt consists of a single type of particle (sodium chloride) and its constituent particles cannot be separated by any physical methods. Hence, it is pure.

The correct answer is A.

A solution is a homogeneous mixture of two or more substances. Salt forms a homogeneous mixture with water, which means that particles of salt are evenly distributed in the mixture. Hence, salt will form a solution with water.

The correct answer is B.

A pure substance is the one which consists of a single type of particle. Butter is not a pure substance; it is a mixture of more than one kind of a pure form of matter. The constituent particles of butter can be separated by physical methods.

The correct answer is C.

With an increase in the temperature of a solution, the solubility increases. Therefore, the solubility of a substance at 100°C would be more than 30.

The correct answer is D.

 In the solution of ‘tincture of iodine’, iodine is dissolved in alcohol (which is present in a larger quantity). Hence, alcohol is the solvent in a solution of ‘tincture of iodine’

The correct answer is C.

The mixture of sand and water is heterogeneous in nature. The solute particles of a heterogeneous mixture are visible to the eye. The solute particles settle down when left undisturbed. Such mixtures are separated by the process of filtration.

Hence, the mixture of sand and water can be separated by the process of filtration.

The correct answer is C.

Mass of solute = 12 g (given)

Mass of solvent = 188 g (given)

Thus, Mass of solution = mass of solute + mass of solvent

= (12 + 188) g

= 200 g

Therefore, the concentration (mass by mass percentage) of the solution

$$\begin{gathered} = \frac{mass os solute}{mass of solution}\times 100 \\ = \frac{12}{200}\times 100 \\ = 6\% \end{gathered}$$

 

Hence, the correct answer is option A.

Mass of solute = 33.6 g (given)

Concentration of solution (mass by volume) = 9.6% (given)

It is known that,

Concentration of solution (mass by volume) =

= 350 mL

Thus, the volume of the solution is 350 mL.

The correct answer is C.

Tyndall effect is the scattering of light as light beam passes through a colloid or in a very fine suspension. Soda water is a homogeneous mixture of carbon dioxide and water. Thus, it is a solution and solutions do not show the ‘Tyndall effect’. Hence, soda water does not show the ‘Tyndall effect’.

Hence, the correct answer is option C.

Shaving cream is a colloidal solution in which the dispersed phase is gaseous and the dispersing medium is liquid.

Foams are colloidal solutions in which the dispersed phase is gaseous and the dispersing medium is liquid. Hence, shaving cream is a foam.

The correct answer is B.

Fog is a colloidal solution in which the dispersed phase is liquid and the dispersing medium is gaseous. Aerosols are colloids in which the dispersed phase is liquid and the dispersing medium is gaseous. Hence, fog is an aerosol.

The correct answer is D.

Camphor is a sublimable volatile solid whereas sodium chloride is a non-sublimable solid. Sublimation is a technique used to separate the components of a mixture containing a sublimable volatile solid and a non-sublimable impurity. Therefore, the mixture of camphor and sodium chloride can be separated by the process of sublimation.

The correct answer is D.

The process of evaporation is used to separate a non-volatile component (solute) from a volatile component (solvent). Ink is a mixture of a dye in water. In the process of evaporation, water from the ink evaporates leaving the dye behind.

The correct answer is C.

The inter-conversion of states of any substance represents a physical change. Melting of ice is a physical change. This is because, in this case, only the state of water changes (from a solid to a liquid) and no new compound is formed.

The correct answer is A.

The technique of distillation is used to separate a mixture of two miscible liquids having a large difference in their boiling points (greater than 25 K). For mixtures having liquids with a difference in their boiling points less than 25 K, the process of fractional distillation is used.

The difference in the boiling points of P and Q = (360 − 330) K

= 30 K

Hence, P and Q can be separated by the technique of distillation.

The correct answer is B.

According to Lavoisier, a French chemist, an element is a basic form of matter that cannot be broken down into simpler substances by chemical reactions.

Gold (Au) cannot be broken down into simpler substances by chemical reactions. Hence, it is an element.

The correct answer is A.

A chemical change is defined as the one in which a new substance with different chemical properties from the reacting species is formed. In the process of souring of milk, its chemical composition gets altered and a new compound is formed. Thus, it represents a chemical change.

The correct answer is A.

Mercury is the only metal which is liquid at room temperature.

The correct answer is C.

Metals have lustre and are good conductors of heat and electricity. They are ductile and malleable. Copper shows all these properties. Hence, it is a metal.

The correct answer is B.