NCERT Class VI Science Solutions: Chapter 5-Separation of Substances Part 1

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Question 1:

Why do we need to separate different components of a mixture? Give two examples.

Answer:

Before using a substance, we need to separate harmful or non-useful substances that may be mixed with it. Sometimes, we separate even useful components if we need to use them separately.

Picture shows separate sand and salt with water

Separate Different Components of a Mixture

Picture shows separate sand and salt with water

For example:

  • We used to separate slightly larger sized impurities like the pieces of dirt, stone, and husk from wheat, rice or pulses by handpicking method.

  • Rice or pulses are usually washed before cooking. When we add water to these, the impurities like dust and soil particles get separated.

Question 2:

What is winnowing? Where is it used?

Answer:

Winnowing is the method of separating components of a mixture containing heavier and lighter components by wind or by blowing air. It is used to separate husk particles from seeds of grain.

As showing in a Image result for winnowing.

Method of Winnowing

As showing in a Image result for winnowing.

Question 3:

How will you separate husk or dirt particles from a given sample of pulses before Cooking?

Answer:

Husk or bigger pieces of dirt particles can be removed from a sample of pulses by handpicking.

Question 4:

What is sieving? Where is it used?

Answer:

Sieving is the process of filtering components of a mixture of different sizes. Sieving allows fine particles to pass through the holes of the sieve, while the bigger impurities remain on the sieve.

Sieving is used in flour mills to separate broken particles of grains from flour. It is also used at construction sites to separate lumps, smaller stones from the mixture of sand and cement.

Picture shows sieving separate the mixture

Sieving Image

Picture shows sieving separate the mixture

Question 5:

How will you separate sand and water from their mixture?

Answer:

To separate sand and water from their mixture, we follow the following steps:

  • Leave mixture to stand undisturbed for some time in a container.

  • Sand settles at the bottom of the container. It is called sedimentation.

  • Gently pour the water in another container (called decantation).

  • We may also use filter paper to remove fine particles of sand (called filtration).

Diagram shows separate sand and water from their mixture

Separate Sand and Water from Their Mixture

Diagram shows separate sand and water from their mixture

Question 6:

Is it possible to separate sugar mixed with wheat flour? If yes, how will you do it?

Answer:

Yes. Through sieving we can separate sugar mixed with wheat flour.

Image shows separate sugar mixed with wheat flour

Separate Sugar Mixed with Wheat Flour

Image shows separate sugar mixed with wheat flour

Question 7:

How would you obtain clear water from a sample of muddy water?

Answer:

Following steps are required to obtain clear water from muddy water:

  • Allow muddy water to stand undisturbed in a container.

  • After sometime, mud settles at the bottom of the container. This process is called sedimentation.

  • Upper layer is clear water.

  • Pour the clear water gently in another container.

  • This process is called decantation.

  • To remove finer impurities we can filter this water again with the help of filter paper. This process is called filtration.

Diagram shows clear water from a sample of muddy water

Process of Filtration

Diagram shows clear water from a sample of muddy water