A. Short answer questions
1. What are the conditions required for separating substances by handpicking?
2. Name three ways of threshing.
3. Explain the process of winnowing.
4. In which cases can we apply the method of sieving for separating substances?
5. When do we use the method of magnetic separation?
Answers
Explanation:
1.
handpicking be used to separate the constituents of a mixture as some of the substances are easily separate by picking up the impurities by hand. but some of them cannot be removed by hand and we need some other methods of separation for such mixture .
2.
Three ways of threshing are:-
-Threshing rack
-Trampling
-Pedal
3.
The process of separating heavier and lighter components of a mixture by wind or by blowing air is called winnowing.
4.This method is used in a flour mill where impurities like husk and stones are removed from wheat before grinding it. This method is also used at our homes where fine flour particles are separated from bigger impurities by using a sieve.
5.
This method of separation is used when either the ore particles or the gangue associated with it possess magnetic properties.
Answer:
1) Handpicking is a seperation technique used to remove the unwanted impurties from the mixture by hand. It involves simply picking out substances by hand and separating them form others. Handpicking method can be used when items differ on the basis of color ,shape and weight
2) 1.Hammer Mill or Beater type.
2. Spike tooth type.
3. Rasp bar type.
3) The process of separating heavier and lighter components of a mixture by wind or by blowing air is called winnowing.
4) Thistle method is used in a flour mill where impurities like husk and stones are removed from wheat before grinding it. This method is also used at our homes where fine flour particles are separated from bigger impurities by using a sieve.
5) This method of separation is used when either the ore particles or the gangue associated with it possess magneticproperties. For example, chromite Fe(CrO2)2being magnetic can be separated from the non-magnetic silicious gangue by magnetic separation.
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