Chapter 7: Rocks and Soil - Exercise Answers

Warm-up

Q: Write down four things that you observe in the soil.

Ans: 1. Different colours of soil
2. Small stones and pebbles
3. Dry and wet patches
4. Leaves and small insects

Activity: To study the softness of rocks

Q: Which of the two - chalk and marble can you crush easily? Why?

Ans: Chalk can be crushed easily. Because chalk is a soft rock while marble is a hard rock.

Check Your Progress: True or False

  1. Rocks are made up of minerals. T
  2. Minerals are large particles. F
  3. Granite is a soft rock. F
  4. Chalk is a hard rock. F

A. Tick (✓) the correct options.

  1. Which of the following is a hard rock? a. granite
  2. Which rock cannot be broken easily? b. granite
  3. Which is not a factor in the formation of soil? d. chlorophyll
  4. Which layer of soil is formed by dead remains? c. humus
  5. Which soil can retain a lot of water? b. clayey

B. Fill in the blanks

  1. Rock is made of minerals.
  2. Chalk is a soft rock.
  3. Changes in the weather and the heat of the Sun break the rocks.
  4. Clayey soil is used by potters to make utensils.
  5. Loamy soil is a mix of sandy and clayey/humus soil.

C. True or False

  1. Minerals are large particles. F
  2. Sandy soil is made of small particles of sand. F
  3. Loamy soil is ideal for growing plants. T
  4. The roots of a plant cannot stay fixed because of soil. F
  5. Soil provides a home to small animals. T

D. Who am I?

  1. I am used for writing on the blackboard. Chalk
  2. Bottom layer of the soil with tiny stones. Gravel
  3. Very fertile and ideal for growing plants. Loamy soil
  4. Small crawling animal living in soil. Earthworm
  5. Made of fine particles, used for utensils. Clayey soil

E. Short-Answer Questions

  1. The top layer of the Earth: Soil
  2. Two hard rocks: Granite, Marble
  3. Two soft rocks: Chalk, Slate
  4. The bottom layer of the soil: Gravel
  5. The soil for making utensils: Clayey soil

F. Long-Answer Questions

1. Different types of rocks with examples
There are Hard rocks like granite and marble which cannot be broken easily. Soft rocks like chalk and slate which can be broken easily.

2. Process of soil formation
Soil is formed by weathering. Heat of the Sun, rain and wind break rocks into smaller pieces over a long time.

3. Different layers of soil with activity
Take soil in water and shake. Layers settle as: Gravel at bottom, then sand, then clay, and humus on top.

4. Sandy soil vs Clayey soil
Sandy soil: Large particles, allows water to pass, not good for plants.
Clayey soil: Fine particles, retains water, used for making pots.

5. Uses of soil
1. To grow plants and crops
2. Home to small animals
3. Used to make pots and utensils
4. Gives us food

G. Think

Q: Farmer wants to sow crops. Sandy soil or Loamy soil? Why?

Ans: The farmer will choose loamy soil. Because it is a mix of sand and clay, contains humus, and is very fertile for growing plants.

--- End of Chapter 7 Answers ---