Class 6 Science Chapter 3 Question Answers

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.
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.

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.

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

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.

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

1. Leave mixture to stand undisturbed for some time in a container.
2. Sand settles at the bottom of the container. It is called sedimentation.
3. Gently pour the water in another container (called decantation).
4. We may also use filter paper to remove fine particles of sand (called filtration)

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

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

1. Allow muddy water to stand undisturbed in a container.
2. After sometime, mud settles at the bottom of the container. This process is called sedimentation.
3. Upper layer is clear water.
4. Pour the clear water gently in another container. This process is called decantation.
5. To remove finer impurities we can filter this water again with the help of filter paper. This process is called filtration.

(a) The method of separating seeds of paddy from its stalks is called ___________.
(b) When milk, cooled after boiling, is poured onto a piece of cloth the cream (malai) is left behind on it. This process of separating cream from milk is an example of ___________.
(c) Salt is obtained from seawater by the process of ___________.
(d) Impurities settled at the bottom when muddy water was kept overnight in a bucket. The clear water was then poured off from the top. The process of separation used in this example is called ___________.

Answer:
(a) The method of separating seeds of paddy from its stalks is called threshing.
(b) When milk, cooled after boiling, is poured onto a piece of cloth the cream (malai) is left behind on it. This process of separating cream from milk is an example of churning.
(c) Salt is obtained from seawater by the process of evaporation.
(d) Impurities settled at the bottom when muddy water was kept overnight in a bucket. The clear water was then poured off from the top. The process of separation used in this example is called sedimentation and decantation.

(a) A mixture of milk and water can be separated by filtration.
(b) A mixture of powdered salt and sugar can be separated by the process of winnowing.
(c) Separation of sugar from tea can be done with filtration.
(d) Grain and husk can be separated with the process of decantation.

Answer:

• (a) A mixture of milk and water can be separated by filtration. (False)
• (b) A mixture of powdered salt and sugar can be separated by the process of winnowing. (False)
• (c) Separation of sugar from tea can be done with filtration. (False)
• (d) Grain and husk can be separated with the process of decantation. (False)

Answer:
We should add sugar before adding ice. Sugar dissolves in warm water more quickly than in cold water. We can dissolve more sugar before mixing ice in water.