Test: Separation of Substances - UPSC MCQ

• Winnowing is the method in which heavier components of the mixture are separated from the lighter substances with the help of wind.
• This method is used for separating grains from husk after the process of threshing.

Threshing involves beating the stalks to free the grain seeds. This method has been traditionally used to separate the valuable grain from the rest of the plant material, facilitating the collection of the seeds for further processing.

The water drops observed when steam comes into contact with a metal plate cooled with ice are due to the condensation of steam. This process occurs because the steam, which is in the gaseous state, loses heat energy to the cold metal plate and surroundings, causing it to change into its liquid form (water). This phenomenon is a common occurrence when warm, moist air meets a cooler surface.

• When we want to separate salt from water in a mixture, we can use a method called evaporation.
• This means heating the mixture until the water boils away, leaving the salt behind.
• It's like when water in a pot boils and turns into steam, leaving things like salt or sugar behind.
• So, to separate salt from water, we can use evaporation to make the water disappear, and then we'll find the salt left behind.

Evaporation is a process where a liquid changes into a vapor, not a solid. When you heat a liquid like water, it turns into water vapor which you can see as steam. This process leaves behind any solid substances that were dissolved in the liquid. So, the statement is False.

The process by which the unwanted solid particles are removed from the liquid is called as filtration.

• Difference in weight is the properties used to separate two solids from a mixture by winnowing.
• Husk or dirt particles can be separated by winnowing method. It is used to separate the heavier and lighter components of a mixture by wind or by blowing air.
• In this method, the mixture of husk and seeds of grain are take in plate and are made to fall down from a height up to our shoulders.

Most of the substances that we see around us are a mixture of two or more substances.

When making tea, tea leaves are separated from the liquid using a sieve. The sieve helps to keep the tea leaves out of the cup, so you can enjoy a nice, smooth cup of tea without any pieces of leaves in it.

Mixtures need to be separated for various reasons including removing undesirable substances, obtaining desirable substances, and obtaining highly pure substances.

These methods like handpicking, winnowing, sieving, sedimentation, decantation, and filtration help to separate different things mixed together, like separating salt from water or sand from a mixture. So, these methods help in separating substances from their mixtures.

When we make tea, we use a strainer to separate the tea leaves from the liquid. This is true because we don't want the leaves in our tea when we drink it. The strainer helps keep the leaves out, so we only get the tasty tea to drink!

• Chalk powder is a carbonate compound, insoluble in water.
• Because of this property of chalk powder, it is easy to separate it from water.
• The mixture containing chalk powder and water is allowed to get filtered.
• (Filter paper can be used for filtration) After filtration, the retentate obtained is chalk and the filtrate obtained is water without chalk.
• The retentate is allowed to get dried and hence, chalk is obtained in powder form.