| Publisher | : Oriental Book Company Private Limited |
| Material | : Madhyamik Physical Science Solution |
| Subject | : Physical Science |
| Class | : 9 (Madhyamik) |
| Chapter Name | : Separation Of Components Of Mixture |
In-Text Questions
Question 4.5.1
Mention the methods of separation of non-volatile solids from its true solution.
Answer
Non-volatile solids can be separated from their true solutions using the following methods:
- Evaporation – The solution is heated, and the solvent is allowed to evaporate, leaving behind the solid residue.
- Crystallization – The solution is allowed to cool or evaporate slowly to form pure crystals of the dissolved solid.
Question 4.5.2
How is the fat of milk separated?
Answer
Fat is separated from milk using the centrifugation method. Milk is spun at high speed in a centrifuge, causing the denser components to move outward while the lighter fat rises to the top, which can be collected as cream.
Question 4.5.3
Mention the method to collect the different fractions of crude petroleum.
Answer
The different fractions of crude petroleum are collected using fractional distillation. The crude petroleum is heated in a fractionating column where different hydrocarbons separate based on their boiling points. The lighter fractions rise higher in the column while heavier fractions condense at lower levels.
Exercise
Very Short Answer Questions
Choose the correct answer:
Question 1 (i)
The method to separate sugar from its aqueous solution while ignoring the collection of water is:
(a) evaporation
(b) distillation
(c) sedimentation
(d) centrifugation
Answer
(a) evaporation
Question 1 (ii)
Iodine and ethanol are separated from their mixture by:
(a) filtration
(b) evaporation
(c) distillation
(d) fractional distillation
Answer
(c) distillation
Question 1 (iii)
A mixture of carbon tetrachloride and water is separated by using:
(a) funnel
(b) separating funnel
(c) beaker
(d) fractionating column
Answer
(b) separating funnel
Question 1 (iv)
The boiling point of a liquid:
(a) decreases with an increase in pressure
(b) boiling point has no effect on pressure
(c) increases with an increase in pressure
(d) does not always increase with an increase in pressure
Answer
(c) increases with an increase in pressure
Question 1 (v)
The components of crude oil are separated by:
(a) fractional distillation
(b) distillation
(c) fractional crystallization
(d) none of these
Answer
(a) fractional distillation
Complete the following sentences with the appropriate terms such as
[evaporation, filtration, decomposition, separating funnel]
Question 2 (i)
Silver nitrate solution is added to sodium chloride solution to give a curdy white precipitate; the precipitate is separated from the mixture is called ____.
Answer
filtration
Question 2 (ii)
 Glycerol is distilled under reduced pressure to avoid ____.
Answer
decomposition
Question 2 (iii)
The suspension of chalk in water is separated by ____.
Answer
filtration
Question 2 (iv)
Kerosene is lighter and immiscible in water, they are separated by using ____.
Answer
separating funnel
Question 3
How will the following be separated?
(a) Ferric hydroxide precipitate from water.
(b) Common salt from its aqueous solution.
(c) Pure water from salt water.
(d) Dye from black and violet inks.
(e) Cream from milk.
Answer
(a) Filtration
(b) Evaporation or Crystallization
(c) Distillation
(d) Chromatography
(e) Centrifugation
Short Answer Type Questions
Question 1
Name two different methods in case for the separation of:
(a) Solid-Liquid mixtures
(b) Liquid-Liquid mixtures
(c) Petrol and water
(d) Salt and water
Answer
(a) Filtration, Evaporation
(b) Separating Funnel, Distillation
(c) Separating Funnel
(d) Evaporation or Distillation
Question 2
What is centrifuge? How are blood particles separated?
Answer
A centrifuge is a device that spins a mixture at high speed, causing components to separate based on their densities.
Blood particles are separated by centrifugation, where denser blood cells settle at the bottom, and plasma remains on the top.
Question 3
How will you get salt from seawater?
Answer
Salt is obtained from seawater by evaporation. Seawater is collected in shallow evaporation ponds and left under the sun. The water evaporates, leaving behind salt crystals, which are then purified.
Long Answer Type Questions
Question 1
Explain:
(a) Fractional distillation
(b) Centrifugation
Answer
(a) Fractional distillation is used to separate two or more miscible liquids based on their boiling points. The mixture is heated, and the component with the lowest boiling point evaporates first, then condenses and is collected separately.
(b) Centrifugation is a process where a mixture is spun at high speed, causing denser particles to move outward and separate from lighter particles. It is commonly used to separate cream from milk and blood components.
Question 2
Name three commercial materials obtained from the fractional distillation of crude petroleum and state their use.
Answer
(a) Petrol (Gasoline) – Used as fuel in vehicles.
(b) Diesel – Used in heavy-duty engines and generators.
(c) Kerosene – Used as fuel for cooking, heating, and jet aircraft.
Question 3
(a) Name the apparatus used to separate petrol and water. Separation depends on which property of the liquid?
(b) How does the boiling point of a liquid depend on pressure?
Answer
(a) Apparatus: Separating Funnel
Property: Density difference and immiscibility of the liquids
(b) The boiling point of a liquid increases with an increase in pressure and decreases when the pressure is reduced. At lower pressure, the liquid boils at a lower temperature.
Question 4
You are asked to prepare tea. Write the steps of preparation using the words:
solvent, solute, dissolve, solution, soluble, insoluble, residue, and filtrate.
Answer
- Water is the solvent in which tea leaves and sugar are added.
- Sugar is the solute that dissolves in water, forming a solution.
- Tea leaves are insoluble, so they do not dissolve in water.
- After boiling, the tea is passed through a filter to separate the residue (tea leaves).
- The liquid that passes through the filter is called the filtrate, which is the final tea solution ready to be served.
or
To prepare tea, first, water is taken as the solvent and heated. Then, tea leaves are added, which are insoluble in water, meaning they do not dissolve. Sugar is added as the solute, which will dissolve in the hot water, forming a solution. The mixture is allowed to boil to extract the flavor from the tea leaves. After boiling, the mixture is passed through a strainer, separating the tea leaves. The leftover tea leaves in the strainer are called the residue, while the liquid that passes through is called the filtrate. The final solution is now ready to be served as tea.
