BYJU'S Class 6 Chemistry Worksheet on Separation of Substances, Set 2.

Let's solve the problems step by step and explain each solution.

---

Q-1: The process of conversion of water into its vapour is called _________.

- Options:
a) Precipitation
b) Condensation
c) Evaporation
d) Sublimation

Explanation:
- Evaporation is the process where a liquid (like water) changes into a gas (vapour) at temperatures below its boiling point. This happens due to the increase in kinetic energy of water molecules, causing them to escape from the liquid surface.
- Precipitation is the process of water droplets forming in the atmosphere and falling as rain, snow, etc.
- Condensation is the process where a gas changes into a liquid.
- Sublimation is the direct change of a solid into a gas without passing through the liquid state.

Correct Answer:
c) Evaporation

---

Q-2: Which of the following is the basis of separation for filtration?

- Options:
a) Difference in size of the particles.
b) Difference in mass of the particles.
c) Difference in weight of the particles.
d) Difference in density of the particles.

Explanation:
- Filtration is a method used to separate insoluble solids from liquids. It works based on the difference in the size of the particles. The solid particles are retained by the filter medium (e.g., filter paper), while the liquid passes through.
- The other options (mass, weight, and density) are not directly relevant to the principle of filtration.

Correct Answer:
a) Difference in size of the particles.

---

Q-3: Which of the following factors would be used in winnowing to separate heavier and lighter components of a mixture?

- Options:
a) Water
b) Wind
c) Air
d) Sea water

Explanation:
- Winnowing is a method used to separate lighter components (like chaff or dirt) from heavier components (like grains) using air currents. The wind or blowing air helps to carry away the lighter particles, leaving the heavier ones behind.
- Water, sea water, and air (in general) are not specifically used in the context of winnowing.

Correct Answer:
b) Wind

---

Q-4: Name the method that can be used for the following:

- a) Water and Black gold
- b) Chana and salt
- c) Green chillies from poha

Explanation:
1. Water and Black gold (Coal):
- Black gold refers to coal. To separate coal from water, you can use filtration because coal is a solid and will be retained by the filter, while water will pass through.

2. Chana and salt:
- Chana (chickpeas) and salt are both solids but have different sizes. You can use sieving to separate them because the smaller salt particles will pass through the sieve, while the larger chana particles will remain on top.

3. Green chillies from poha:
- Poha is flattened rice, and green chillies are larger and distinct. You can use handpicking or sieving to separate them, as the sizes and shapes are different.

Answers:
- a) Filtration
- b) Sieving
- c) Handpicking/Sieving

---

Q-5: Which of the following techniques is used to separate two immiscible liquids?

- Options:
a) Decantation
b) Filtration
c) Sedimentation
d) All of the above

Explanation:
- Decantation is used to separate two immiscible liquids (liquids that do not mix, like oil and water). The denser liquid settles at the bottom, and the less dense liquid is poured off from the top.
- Filtration is used to separate solids from liquids, not liquids from liquids.
- Sedimentation is used to separate solid particles from a liquid by allowing them to settle at the bottom due to gravity.
- Therefore, only decantation is suitable for separating immiscible liquids.

Correct Answer:
a) Decantation

---

Q-6: Fill in the blanks.

#### a) Machines are used to thresh large quantities of _________.
- Explanation:
Threshing is the process of separating grains from their stalks. Machines are used to thresh large quantities of grains.

#### b) _______ are dried in the sun before they get separated from the grain.
- Explanation:
Before separating grains from their stalks, the harvested crops are often dried in the sun to reduce moisture content. The blank should be filled with crops or harvested plants.

#### c) The substances to be separated may be particles of different ________ or ________.
- Explanation:
Substances can be separated based on differences in their physical properties such as size or density.

#### d) When steam comes into contact with an ice-cooled metal plate, it ________ and turns into liquid water.
- Explanation:
When steam (water vapour) comes into contact with a cold surface, it loses heat and changes back into liquid water. This process is called condensation.

Filled Blanks:
- a) Machines are used to thresh large quantities of grains.
- b) Crops are dried in the sun before they get separated from the grain.
- c) The substances to be separated may be particles of different size or density.
- d) When steam comes into contact with an ice-cooled metal plate, it condenses and turns into liquid water.

---

Final Answers:

1. c) Evaporation
2. a) Difference in size of the particles.
3. b) Wind
4. a) Filtration; b) Sieving; c) Handpicking/Sieving
5. a) Decantation
6. a) Grains; b) Crops; c) Size, Density; d) Condenses

Boxed Final Answer:
\[
\boxed{
\text{1. c) Evaporation, 2. a) Difference in size of the particles, 3. b) Wind, 4. a) Filtration, b) Sieving, c) Handpicking/Sieving, 5. a) Decantation, 6. a) Grains, b) Crops, c) Size, Density, d) Condenses}
}
\]