Explore topic-wise InterviewSolutions in Current Affairs.

Sodium chloride.

1. False. 

Correct — Components in a mixture are present in a varying proportion.

2. True

3. False. 

Correct — Components in a mixture can be separated by physical methods.

4. False. 

Correct — Sodium chloride and water is an example of a mixture of compounds.

5. True

(a) True

(b) False 

Correct : Common salt is separated from its solution in water by evaporation.

(c) False 

Correct : Winnowing is a process to remove husk from grains.

(d) False 

Correct : Jewellery gold is a heterogeneous mixture of metals.

(e) False 

Correct : Air can be separated from water by heating.

(f) True

(g) False 

Correct: Steel is an alloy of iron and carbon.

Water from a river, pond or lake contains very fine clay particles. To make them settle at a faster rate, a chemical substance called alum in powdered form is added to such mixtures. It dissolves in water and forms clusters with clay and dust particles making them heavier and increasing the rate of sedimentation.

(a) Sublimation 

(b) Magnetic separation 

(c) Evaporation 

(d) Seiving 

(e) Magnetic separation 

(f) Seiving

Carbon is a  black non-metallic component of the mixture gunpowder.

(a) The substances that make a mixture are called its constituents or components. 

(b) Evaporation or crystallisation is a process to separate solids dissolved in liquids. 

(c) Mist is a heterogeneous (liquid in gas) mixture of droplets of water and air. 

(d) Clay is separated from water by the method of loading and decantation. 

(e) When cereals are washed before cooking, water is separated from the cereals by decantation. 

(f) Crystallisation is a process to obtain a very pure form of a solid dissolved in a liquid. 

(g) Ammonium chloride can be separated from common salt by the method of sublimation. 

(h) The solid particles which remain on the filter paper are called residue and the liquid which passes through it is called filtrate. 

(i) The process of transferring the clear liquid layer above the solid particles which settle at the bottom of the container is known as decantation. 

(j) Filtration is a method used for the separation of an insoluble solid from a solid-liquid mixture.

The insoluble solid particles in a solid-liquid mixture can be seperated by filtration. 

Technique of Seperation — A filter paper is made into a cone & placed in a funnel. The solid particles remain behind on the filter paper while the liquid collects below.

(a) Camphor and Naphthalene

(b) Sugar and salt (NaCl) 

(c) Sand and chalk powder. 

(d) (i) Filter paper, 

(ii) A bead of sand, 

(iii) Charcoal, 

(iv) A piece of muslin cloth.

Because in hand picking method substances should be large enough in size to be recognized and picked out by hand but sand and saw dust particles are very small in size so they can’t be picked by hand. It can be separated by filtration.

(a) Term — 

Elements – Pure substance made up of one kind of atoms only. e.g. Iron [Fe], Sulphur [S] 

Compounds – Pure substance made up of two or more different elements, e.g. Iron sulphide [FeS] 

Mixtures – Impure substance made up of two or more elements or compounds, e.g. Iron and sulphur mixture. 

(b) Existence — 

Elements – Elements i.e. atoms are present on their own. e.g. Iron and sulphur exist on their own as elements iron and sulphur. 

Compounds – Components in a compound present in a definite proportion. e.g. Iron and sulphur are chemically combined in a fixed ratio in iron sulphide. 

Mixtures – Components in a mixture present in any proportion. e.g. Iron and sulphur are mixed in any ratio in the mixture of iron and sulphur. 

(c) Properties — 

Elements – Elements have a definite set of properties. Elements classified into metal and non-metals each with its own properties. 

Compounds – Compounds have a definite set of properties. Elements of a compound do not retain their original properties. 

Mixtures – Mixture not have a definite set of properties. Components of a mixture do retain their original properties. 

(iv) Separation of compound — 

Elements – Elements occur on their own or as compounds and can be separated by chemical and physical methods. Example : Iron, copper. 

Compounds – Elements in a compound are chemically combined and can be separated by chemical methods only. Example : Iron Sulphide, copper oxide. 

Mixtures – Components in a mixture can be separated by physical methods only. Example : Iron + sulphur

A homogeneous mixture has the same uniform appearance and composition throughout. Many homogeneous mixtures are commonly referred to as solutions. A heterogeneous mixture consists of visibly different substances or phases. The three phases or states of matter are gas, liquid, and solid.

Homogeneous mixture : Salt solution, alcohol and water, air dissolved in water, sea water, brass. 

Heterogeneous mixture: Sand and charcoal, air, fruit juice, mist, petrol and water.

(a) Iron and sulphur. 

(b) Sand and water, rice and water. 

(c) Sugar from its solution in water.

Copper is not a part of the alloy : 

 3. steel

A gas dissolved in a liquid can be separated by :

2. boiling

Filtration is a method that is used to separate insoluble solids from liquids, since both salt dissolve in water.

(a) Filtration : The process of separating solid particles from liquid by allowing it to pass through a filter paper is called filtration. 

(b) Sublimation : The process in which a solid changes directly into its vapours on heating is called sublimation. 

(c) Evaporation : Is the process of converting a liquid into its vapours state either by exposing it to air or by heating. 

(d) Crystallisation : Evaporation of liquid from a homogeneous liquit-solid mixture and collecting solid in the form of crystals is called crystallisation. 

(e) Miscible liquids: Homogeneous liquid-liquid mixtures are called miscible liquids. 

(f) Immiscible liquids : Heterogeneous liquid-liquid mixtures are called immiscible liquids.

(a) Sedimentation and decantation — 

Principle — The solid component is insoluble and heavier than the liquid component. 

Example — Mixture of sand and water 

(b) Filtration — 

Principle — Seperation of insoluble solid component by passing through a porous material like filter paper. 

Example — Mixture of chalk and water, Mixture of Agcl and Water. 

(c) Evaporation — 

Principle — Seperation of the mixture by evaporating the liquid component. The solid should be soluble in the liquid and should not sublime.

Sulphur has the property to dissolve in carbon disulphide whereas iron does not dissolve and retains its individual property. However, On heating Iron and Sulphur, they chemically combined forming Iron Sulphide. In this, Iron and Sulphur particles do not exists separately as such they loose their individual property.