Separation of Substances quiz

Stones are removed from rice by:

Husk is separated from grains by:

Butter is separated from curd by:

Salt is obtained from sea water by:

The process of settling of heavier particles in a liquid is called:

The change of water vapour into liquid water is:

Separating grain from stalks is called:

A solution in which no more salt can dissolve at a given temperature is:

Tea leaves are separated from prepared tea using a:

Which of the following increases the amount of salt that dissolves in water?

Why is winnowing done in the wind? (2 marks)

Give two examples of sieving used at home or at a construction site. (2 marks)

Why is filtration better than decantation for removing fine particles? (2 marks)

What is the residue and the filtrate in filtration? (2 marks)

How is threshing done on small and large farms? (2 marks)

Why do water droplets form on the lid of a pan with boiling water? (2 marks)

Why can we not separate salt from salt water by filtration? (2 marks)

Name two mixtures that can be separated by handpicking. (2 marks)

How does alum help in clearing muddy water? (2 marks)

Why do we need more than one method to separate some mixtures? Give one example. (2 marks)

A student dissolved 9 g of salt in 25 mL of water to make a saturated solution. How much salt is needed to saturate 100 mL and 250 mL of water at the same temperature? (3 marks)

A farmer threshes 500 kg of wheat stalks and gets 150 kg of grain. What percentage of the mass is grain? How much is chaff and straw? (3 marks)

4 litres of sea water gives 140 g of salt on evaporation. How much salt is present in 1 litre? How much sea water is needed to get 1.05 kg of salt? (3 marks)

A mixture contains 200 g of sand and 50 g of salt in 500 mL of water. After filtration and evaporation, find the masses of the residue on the filter paper and the solid left after evaporation, assuming no loss. (3 marks)

In a sieving activity, 1 kg of flour gave 850 g of fine flour and the rest was bran. Find the mass of bran and the percentage of fine flour. (3 marks)

Read the passage and answer the questions. In a village, after harvesting wheat, farmers beat the bundles of stalks on a hard surface. Later, women stand on a raised platform and drop the mixture of grain and husk from a height while the wind blows. (i) Name the first process. (ii) Name the second process. (iii) Why does the husk form a separate heap from the grain? (5 marks)

Read the passage and answer the questions. Sita's mother made tea by boiling water, milk, sugar and tea leaves. She then poured the tea through a strainer into cups. Later, she churned curd in a vessel to get butter. (i) Which method was used to separate tea leaves? (ii) Which method was used to get butter? (iii) Why does butter separate on churning? (5 marks)

Read the passage and answer the questions. In Gujarat, sea water is let into shallow pits called salt pans. The water is left for many days in the hot sun. After some time, a white solid is left behind, which is collected and purified. (i) Name the process that leaves salt behind. (ii) Why are the pits made shallow? (iii) Why is sunlight important here? (5 marks)

Read the passage and answer the questions. A student collected muddy water from a pond in a beaker. After an hour, the mud had settled at the bottom. She poured the clear water into another beaker and then passed it through filter paper. (i) Name the process of settling of mud. (ii) Name the process of pouring off the clear water. (iii) Why did she filter the water after pouring it off? (5 marks)

Read the passage and answer the questions. Ravi added salt to a glass of water at room temperature, stirring continuously. After some time, salt began to collect at the bottom. He then heated the water gently and found that the salt at the bottom dissolved. (i) What kind of solution did he have when salt stopped dissolving? (ii) What does heating do to the amount of salt that can dissolve? (iii) What would happen if the hot solution were cooled? (5 marks)

Describe how you would separate a mixture of sand and salt and get back both. Draw labelled diagrams of filtration and evaporation and name each step. (6 marks)

Explain handpicking, threshing, winnowing and sieving with one example each. Draw a labelled diagram of winnowing and explain why it works. (6 marks)

Describe the processes of sedimentation, decantation and filtration with labelled diagrams. Explain when each method is used, with one daily-life example each. (6 marks)

Describe an activity to show evaporation and condensation. Draw a labelled diagram of the setup and explain how these processes help in obtaining pure water. (6 marks)

Describe an activity to show that water can dissolve only a limited amount of salt and that heating increases the amount. Draw a diagram, record observations in a neat list, and explain the term saturated solution. (6 marks)