Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Soil is the uppermost layer of the Earth's surface in which plants grow. It is formed by the process of weathering of rocks.
The composition of soil includes rock particles of different sizes, such as sand, silt, and clay.
Humus is a vital part of soil composition. It is the dark, organic matter formed from the remains of dead plants and animals that provides nutrients for and nutrient absorption by plants.
Soil contains air trapped between its particles, which is essential for the roots of plants and small organisms to breathe.
Soil contains moisture or water (), which is absorbed by the roots of plants for growth.
Living organisms like earthworms, ants, and bacteria live in the soil and help in making it fertile.
📐Formulae
💡Examples
Problem 1:
Explain an experiment to show that soil contains air.
Solution:
Take some dry soil in a glass jar and pour water () over it.
Explanation:
When water is poured, you will see bubbles forming. These bubbles are the air that was trapped between the soil particles being displaced by the molecules.
Problem 2:
What happens when you heat garden soil in a covered tin container?
Solution:
Tiny drops of water () will be seen on the underside of the lid.
Explanation:
This proves that soil contains moisture. When heated, the in the soil turns into water vapor, which then condenses on the cool lid.
Problem 3:
Why is humus considered the most important part of soil for farmers?
Solution:
Humus makes the soil fertile.
Explanation:
Humus contains essential nutrients that plants need to grow healthy and strong. It also improves the soil's ability to hold .