Class 6 Science Chapter 3 MCQ

If the saturated solution of a substance at a particular temperature is heated to a higher temperature, than the solubility of substance increases and more of substance can be dissolved in it. If the saturated solution of a substance at a particular temperature is cooled a lower temperature, than the solubility of the substance decreases and some of the dissolved substance will separate out in the form of solid crystals.

A mixture of iron filling and rice flour can be separated by “Magnet”. Rest of all are correct.

Water droplets on the outer surface of glass is formed due to condensation of atmospheric water vapour. Actually, the water vapour present in air, on coming in contact with the cold glass of water, loses energy and gets converted to liquid state, which we see as water droplets.

We can separate oil mixed in water by “decantation”. With the help of evaporation, we can separate salt mixed with water.

The droplets of water on the inner surface of bottle were formed due to evaporation and condensation. Note: The process of conversion of water vapour into liquid form is called “condensation”.

By the process of evaporation we can get back solid copper sulphate from the solution. The process of evaporation for separating a mixture is based on the fact that liquids vaporise easily whereas solids do not vaporise easily.

Water is capable of dissolving a variety of different substances as it is called “Universal solvent” not solution. Rest of all statements are correct.

Here, all the statements are correct. Hence, your answer will be option [D].

Milk is a mixture of cream in a watery liquid. Rest of all statements are correct. Hence, your answer will be option [D].

By decantation and then by filtration can be separated from the residue. Note: Decantation is the process of pouring out the liquid without disturbing the sediment.

The most suitable method to separate the grains from the flour is by “Sieving”. Sieving is used to separate those solid mixture which have components of different sizes.

We cannot separate mixture of milk and water by filtration because milk is completely soluble in water. Grain and husk can be separated with the process of winnowing. We cannot separate tea from sugar because they are completely mixed and forming homogeneous solution. Here, all the statements are incorrect. Hence, your answer will be option [D].

Water droplets on the outer surface of glass is formed due to condensation of atmospheric water vapour. Actually, the water vapour present in air, on coming in contact with the cold glass of water, loses energy and gets converted to liquid state, which we see as water droplets. Hence, your answer will be option [C] evaporation and condensation.

Winnowing is used to separate heavier and lighter components of a mixture by wind or by blowing air. Rice flakes and potato wafers are lighter substances in the mixture, so these are separated from the given mixture by winnowing.

For Separation of two miscible liquids we use “Distillation” process.

The grains are separated from stalks (on which they grow) by the process of threshing. In this process stalks (of wheat, paddy, etc.) are beaten to separate grains from the bundle of stalks. Note: This method is based on the fact that the stalks (or stems) of the crop plant are soft material whereas the grains themselves are very hard. Being soft, stalks can be broken into pieces on beating the grains remains unaffected.

A mixture of oil and water can be separated by “Decantation”. Rest of all statements are correct.

If the saturated solution of a substance at a particular temperature is heated to a higher temperature, than the solubility of substance increases and more of substance can be dissolved in it. If the saturated solution of a substance at a particular temperature is cooled a lower temperature, than the solubility of the substance decreases and some of the dissolved substance will separate out in the form of solid crystals.

Filtration method is used for separating insoluble substances from a liquid. But mixture of two liquids such as oil in water cannot be separated by this method. Also salt in water and sugar in milk are completely dissolved so, cannot be separated by filtration. So, cornflakes in milk can be separated by filtration.

Water droplets on the outer surface of glass is formed due to condensation of atmospheric water vapour. Actually, the water vapour present in air, on coming in contact with the cold glass of water, loses energy and gets converted to liquid state, which we see as water droplets.

Here, all the statements are correct. Hence, your answer will be option [D].

Churning is the method by which cream (fat content) from the milk is separated. So, he should prepare “Lassi” by this process of “Churning”.

We can obtain salt from salt-water mixture (or salt solution) by evaporation but water cannot be recovered during evaporation, it is lost into the air. In order to recover both, salt as well as water, from a salt-water mixture (or salt solution), the process of distillation is used. Distillation is the process of heating water to form water vapour (or steam), and then cooling the hot water vapour (or stem) to get back liquid water.

The solubility of a substance in water decreases on lowering the temperature. If the saturated solution of a substance at a particular temperature is heated to a higher temperature, than the solubility of substance increases and more of substance can be dissolved in it. If the saturated solution of a substance at a particular temperature is cooled a lower temperature, than the solubility of the substance decreases and some of the dissolved substance will separate out in the form of solid crystals.

Hand-picking method would be most appropriate for her to separate vegetables because vegetables can be picked up easily by hand one by one, and can be separated.