Soil - Formation and Composition - UNSOLVED PRACTICE SET
Chapter: Natural Resources | Topic: Soil Formation and Composition
SOIL - FORMATION AND COMPOSITION - UNSOLVED PRACTICE SET
Topic: Soil Formation and Composition
Multiple Choice Questions
Q1. Soil is formed mainly by the process of:
- Photosynthesis
- Weathering of rocks over long periods of time
- Evaporation of water
- Volcanic eruptions only
Q2. The topmost layer of soil, which is dark in colour and rich in humus, is called:
- Bedrock
- Topsoil
- Subsoil
- Parent rock
Q3. Humus in soil is important because it:
- Makes the soil look black
- Provides nutrients to plants and improves soil structure
- Prevents water from entering the soil
- Kills all microorganisms in the soil
Q4. Which of the following is a major component of soil?
- Only sand
- Rock particles, humus, water, air, and living organisms
- Only clay
- Only minerals
Q5. The process of breaking down rocks into smaller particles by wind, water, temperature changes, and living organisms is called:
- Erosion
- Weathering
- Sedimentation
- Condensation
Short Answer Questions
Q6. Describe the process of soil formation. Name the four main factors that help in breaking down rocks into soil.
Q7. What is humus? How is it formed, and why is it called the "heart of fertile soil"?
Q8. Draw a simple diagram of a soil profile in words (or describe the layers). Name the main layers from top to bottom and mention one characteristic of each.
Q9. Why does the soil in the Terai region of Uttar Pradesh (near the Himalayas) have different properties compared to the black soil of Maharashtra? Explain in terms of parent rock and climate.
Long Answer Questions
Q10. Explain the process of soil formation in detail. Describe how physical weathering (by temperature, water, wind), chemical weathering, and biological weathering (by plants, animals, and microorganisms) work together to break rocks into soil. Why does soil formation take hundreds to thousands of years?
Q11. "Soil is a complex mixture, not just crushed rock." Discuss this statement by explaining the components of soil (rock particles, humus, water, air, and living organisms), the role of each component in supporting plant life, and why the proportion of these components determines whether soil is fertile or barren.
APPLICATION / ANALYSIS
Q12. Case Study - Soil Types in India:
Agricultural scientists studied three soil types:
| Soil Type | Location | Colour | Texture | Water Retention | Fertility |
|---|---|---|---|---|---|
| Alluvial soil | Punjab, UP | Light | Sandy-loam | Medium | Very high |
| Black soil | Maharashtra, MP | Dark | Clayey | High | High |
| Laterite soil | Kerala, Karnataka | Red | Coarse | Low | Low |
Answer the following:
(a) Why is alluvial soil very fertile despite medium water retention? What is its main source?
(b) Black soil is excellent for cotton farming. What property of this soil makes it suitable for cotton?
(c) Farmers in Kerala struggle to grow food crops in laterite soil. What one soil improvement technique would you recommend, and why?
Q13. Real-Life Application - School Garden Project:
Your school starts a vegetable garden. The science teacher asks students to analyse the school soil:
| Test | Result |
|---|---|
| Colour | Light brown |
| Texture | Sandy, gritty |
| Water drainage | Very fast |
| Earthworms found | Very few |
| Plant growth | Poor |
Answer the following:
(a) What do the sandy texture and fast water drainage tell you about the soil's ability to hold nutrients and water?
(b) Why are earthworms important for soil health? What does their absence indicate?
(c) Suggest two practical ways to improve this soil so that vegetables can grow well.