Important Questions Test: Separation of Substances - UPSC MCQ

The process of settling down of particles of a solid in a liquid is known as sedimentation.

Seawater contains a large amount of common salt and the salts of other metals dissolved in it. Near the sea-shore, the sea water is collected in shallow pits and allowed to evaporate in the sunshine. In a few days, the water evaporates, leaving behind salt. Hence it is obtained by evaporation.

• Churning: This process involves vigorously mixing a liquid, which helps separate its components based on their densities or states.
• Commonly used in making butter from cream, churning incorporates air and creates movement that breaks apart fat globules, allowing them to clump together.
• It's a physical method, relying on mechanical agitation rather than chemical reactions, making it effective for separating liquid mixtures.
  

X is winnowing, a process which uses the difference in weights of solids in a solid- solid mixture for separating the components.

A solution that has reached the maximum solubility is called a saturated solution . It means you can no longer add solute to the solution . Saturated solution are required for the process of crystallization.

We separate substances in a mixture to obtain useful components, remove useless components and impurities.

Water is a pure substance and all others are solid-in-solid and solid-in-liquid mixtures.

Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. This is the method used to separate a dissolved solid component from its solution as after evaporation only salt remains.

Milk or curd is churned to separate the butter

Answer : D

Handpicking

• Handpicking is a separation technique used to separate a solid-solid mixture.


• In this method, the individual components of the mixture are picked out by hand based on their physical properties.


• It is commonly used when the solid components have distinct differences in size, color, or shape, making them easy to separate manually.


• Handpicking is a simple and cost-effective method, but it may not be suitable for mixtures with very fine particles or similar properties

Filtration is the process of separating suspended solid matter from a liquid, by causing the latter to pass through the pores of some substance, called a filter. The liquid which has passed through the filter is called the filtrate.

Winnowing is the method of separting of a mixture contaning heavier and lighter component by wind is by winnowing air.

Wind winnowing is an agricultural method developed by ancient cultures for separating grain from chaff. It is also used to remove hay and chaff or other pests from stored grain.

Threshing, the loosening of grain or seeds from the husks and straw is the step in the chaff-removal process that comes before winnowing.

Explanation:

Paneer is separated from curdled milk through the process of filtration. When milk is curdled by adding an acid like lemon juice or vinegar, the solid curds (which become paneer) are separated from the liquid whey. Filtration is used to separate the solid curds from the liquid, leaving you with paneer.

Winnowing is the process of separation of the heavier components from the lighter components of a mixture by wind or by blowing air. It is generally used by farmers to separate the lighter impurities such as husk particles from the heavier grains.

The easiest method to separate mixture of sugar and water is evaporation as it will evaporate water and will leave behind the sugar molecules. 

Saturated solution means solution that is not capable of dissolving more solute at given temperature. If we increase the temperature it can dissolve more solute.

The clear liquid which passes through the filter paper is called the filtrate.

• X - Winnowing: This method uses the weight difference between components and depends on air to separate lighter particles (like husk) from heavier ones (like grains). Requires air.

• Y - Threshing: This method involves beating or mechanical action to separate grains from stalks. It does not rely on air for separation. Does not require air.

• Z - Sieving: This method involves passing a mixture through a sieve with appropriate-sized holes to separate particles based on size. It does not rely on air. Does not require air.

Correct Answer: b) Only Y, Z

Sieving is used when particles are too small to be picked by hand and the quantity is large.
Sieving. It is done to separate mixtures that contain substances mostly of different sizes. The mixture is passed through the pores of the sieve. All the smaller substances pass through easily while the bigger components of the mixture are retained.

Condensation is the process by which water vapour changes into liquid water when it comes into contact with a cooler surface. It is a crucial part of the water cycle and plays a significant role in various natural phenomena, such as the formation of clouds and dew.