Exercise

I. Tick (✓) the correct option to complete each sentence.

1. Kerosene and water can be separated from the mixture by

Ans:- decantation.

2. Tiny stones can be removed from wheat by

Ans:- handpicking.

3. An insoluble solid substance can be separated from a liquid by

Ans:- sedimentation.

4. Extremely small suspended particles can be separated from a liquid by

Ans:- loading

5. Birds separate grains from the soil by

Ans:- Picking

6. Salt dissolved in water can be separated by

Ans:- evaporation

II. Classify the following as pure substances and mixtures.

Pure substances:- milk, water vapour, baking soda, water, pineapple juice, gold, sugar, iron, oxygen, silver.

Mixture:- air, soil, sea water, alum crystal.

III. Name the method of separation used to separate the following.

1. Sunflower seeds from a dry flower

Ans:- handpicking

2. Fine wood Ash suspended in water.

Ans:- filtration

3. Weeds from cluster beans.

Ans:- handpicking

4. Mustard seeds from their pods.

Ans:- Threshing

5. Water from rice that has been washed.

Ans:- filtration

6. Copper sulphate powder dissolved in water.

Ans:- evaporation

IV. answer the following questions in one sentence.

1. What is a mixture?

Ans:- A mixture is made up of two or more things which can be separated. The constituents of mixtures retain their properties.

2. What is a pure substance?

Ans:- A pure substance is made up of only one kind of substance.

3. Name the method that farmers use to separate the husk from rice grains.

Ans:- Threshing.

4. What is a sediment?

Ans:- In the processes of sedimentation the undissolved part that settles at the bottom of the liquid is called the sedimentation.

5. Which method will you use to separate two solid substances that differ in size?

Ans:- Sieving.

6. What is a solute.

Ans:- In a solution, the substance which is dissolved in the liquid is called the solute.

V. Answer the following questions in two sentences.

1. Explain winnowing.

Ans:- when a mixture of light and heavy substances is dropped from a height, wind carries the lighter substance away and heavier substances are collected near. This method is called winnowing. It is traditional and cheap and simple but effective method.

2. What are immiscible liquids? How will you separate them?

Ans:-  The liquids that do not mix with each other are called immiscible liquids. Immiscible liquids can be separated by the process of decantation.

3. How will you separate salt from a mixture of salt, sand and water?

Ans:- To separate salt from the mixture of salt sand and water, two methods of separation have to be used. In the first, the sand from the salt water is to be separated by the process of filtration after that there will be only salt and water. Now using the method of evaporation,the salt can be separated from the water.

4. Differentiate between loading and sedimentation.

Ans:- Loading:- 1. It is used to separate extremely small insoluble particles from a liquid.

2. In this method, alum is used to make the sedimentation process faster.

Sedimentation:- 1. It is used to separate undissolved solid particles from a liquid.

2. In this method, simply the mixture is placed undisturbed so that the sediment settles at the bottom. 

5. What are the saturated solutions? What happens when when you heat a saturated solution?

Ans:- A solution is called saturated solution if no more solute can be dissolved in the solution.

When a saturated solution is heated, it becomes unsaturated.

VI. Explain the following methods of separation with an example.

i. Filtration

Ans:- Filtration is used to separate insoluble particles from liquids using a porous device called a filter. 

To separate rice washed in water this filtration method can be used.

ii. Loading

Ans:- Loading method of separation is used to separate extremely small insoluble particles from liquid. In this method alum particle is used which attach them selves to the small particles and the small particles become heavy. After that they settle at the bottom quickly.

Suppose alum is added to water containing fine soil particle. The alum particle will attach with the soil particles and settle at the bottom.which can be separate easily by decantation.

iii. Decantation

Ans:- Decantation is a method to separate the sediment from the liquid. It can also be used to separate immiscible liquids.

Suppose oil is needed to be separated from water. Since oil is lighter so the oil will float over the water. Now slowly the oil can be poured off to another container.

iv. Evaporation

Ans:- The process of changing liquids into gas is called evaporation. If a substance is dissolved in a liquid then evaporation method of separation can be used to separate the dissolved substance from the liquid.

If saltwater is heated then the water will evaporate and salt will be left over. This is an example of evaporation.