Extra 30 short questions and answers on the Chapter:5 Separation of Substances for Class 6 CBSE Science:
Short Answer Questions
Why do we need to separate substances?
Ans:
We need to separate substances to remove impurities, obtain useful components, and improve the quality of substances for use.
What is hand-picking? Give an example.
Ans:
Hand-picking is a method of separation where unwanted substances are removed manually. Example: Removing stones from rice or pulses.
Define winnowing. How is it useful?
Ans:
Winnowing is a method used to separate lighter husk particles from heavier grains using wind or air. It is useful in cleaning grains.
What is sieving? Where is it used?
Ans:
Sieving is the process of separating particles of different sizes using a sieve. It is used in flour mills to remove impurities from wheat flour.
What is sedimentation? Give an example.
Ans:
Sedimentation is the process in which heavier particles settle down in a liquid. Example: Mud settling at the bottom of water.
What is decantation? When is it used?
Ans:
Decantation is the process of carefully pouring out a liquid without disturbing settled solid particles. It is used to separate muddy water.
What is filtration? Give an example.
Ans:
Filtration is the process of separating insoluble solids from liquids using a filter. Example: Separating tea leaves using a strainer.
How can we separate iron fillings from a mixture of sand and iron?
Ans:
By using a magnet, iron fillings can be attracted and separated from sand due to magnetic properties.
Explain the process of churning.
Ans:
Churning is the process of vigorously stirring milk or curd to separate butter from it.
What is evaporation? Give an example.
Ans:
Evaporation is the process of converting a liquid into vapor. Example: Obtaining salt from seawater by evaporating the water.
What is the difference between sedimentation and decantation?
Ans:
Sedimentation:
The process where heavier particles settle down in a liquid.
Decantation:
The process of pouring the clear liquid without disturbing settled particles.
Name two substances that can be separated using filtration.
Ans:
Sand and water, Tea leaves and tea.
How can we separate salt from saltwater?
Ans:
By the evaporation method, the water will evaporate, leaving behind salt.
Which separation method is used in flour mills? Why?
Ans:
Sieving is used in flour mills to remove husk, dirt, and stones from wheat flour.
Why is winnowing not useful for separating iron nails from sawdust?
Ans:
Winnowing works based on weight difference. Since both iron nails and sawdust are heavy, they cannot be separated by wind.
Which method is used to separate immiscible liquids like oil and water?
Ans:
Decantation is used to separate immiscible liquids like oil and water.
What is threshing? How is it done?
Ans:
Threshing is the process of separating grains from stalks. It is done manually, using machines, or by beating the stalks on a hard surface.
How do we obtain clean water from muddy water?
Ans:
By using the sedimentation, decantation, and filtration processes, we can remove the mud particles and obtain clean water.
What is distillation? Where is it used?
Ans:
Distillation is the process of heating a liquid to form vapor and then cooling it to get pure liquid. It is used to obtain pure water from seawater.
How is butter separated from milk?
Ans:
Butter is separated from milk by the churning process, where vigorous stirring helps collect butter on top.
What happens when we filter a mixture of sand and water?
Ans:
The sand gets collected on the filter paper, and clean water passes through it.
Why do we need to separate pebbles from pulses before cooking?
Ans:
Pebbles are impurities and can be harmful if consumed. They need to be separated to make the pulses safe for eating.
Which method is used to separate grains from husk?
Ans:
Winnowing is used to separate grains from husk, as husk is lighter and gets carried away by wind.
Which process is used to separate sugar from sugar solution?
Ans:
Evaporation is used to separate sugar from a sugar solution by heating the solution until water evaporates.
How can we separate chalk powder mixed in water?
Ans:
By filtration, as chalk powder is insoluble and gets collected on the filter paper.
Why do farmers use winnowing after threshing?
Ans:
Farmers use winnowing to remove lighter husk and dust from grains after threshing.
How can we separate sugar from wheat flour?
Ans:
Sieving can be used to separate sugar from wheat flour, as sugar has larger particles than flour.
Why is sedimentation useful in water purification?
Ans:
Sedimentation allows heavier impurities like mud and sand to settle at the bottom, making it easier to remove clean water.
Why do oil and water form separate layers when left undisturbed?
Ans:
Oil is less dense than water, so it floats on top, forming separate layers.
What is the principle behind the filtration process?
Ans:
Filtration works on the principle that solid particles are larger than the tiny pores of a filter, so they get separated while allowing the liquid to pass through.
