If you are looking for Class 8 Geography Unit 1 Rocks and Soil extra question answers then you are at the right place.
Q1: What is a rock?
A1: A rock is an aggregate of one or more minerals. It is an important natural resource found in solid state on the earth’s surface.
Q2: How are rocks classified according to their mode of formation?
A2: Rocks are classified into three types based on their mode of formation:
- Igneous Rocks
- Sedimentary Rocks
- Metamorphic Rocks
Q3: What are the characteristics of igneous rocks?
A3: Characteristics of igneous rocks include:
- They are hard in nature
- They are impermeable
- They do not contain fossils
- They are associated with volcanic activities
Q4: What are the two types of igneous rocks?
A4: The two types of igneous rocks are:
- Extrusive Igneous Rocks
- Intrusive Igneous Rocks
Q5: How are sedimentary rocks formed?
A5: Sedimentary rocks are formed by sediments derived and deposited by various agents (wind, running water, glaciers). These sediments are cemented together over time due to high temperature and pressure.
Q6: What are the characteristics of sedimentary rocks?
A6: Characteristics of sedimentary rocks include:
- They have many layers
- They are non-crystalline rocks
- They contain fossils
- They are soft and get eroded easily
Q7: What is metamorphism in rock formation?
A7: Metamorphism is the process where igneous and sedimentary rocks are subjected to high temperature and pressure, altering them to form a new kind of rock called metamorphic rocks.
Q8: What is the rock cycle?
A8: The rock cycle is an endless process where rocks change from one form to another under various natural forces and agents. It involves the formation, weathering, erosion, and transformation of igneous, sedimentary, and metamorphic rocks.
Q9: What is soil and how is it formed?
A9: Soil is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. It is formed from rocks (parent material) through the processes of weathering and natural erosion.
Q10: What are the basic components of soil?
A10: The basic components of soil are:
- Mineral (about 45%)
- Organic matter (about 5%)
- Water (about 25%)
- Air (about 25%)
Q11: What are the six major types of soil?
A11: The six major types of soil are:
- Alluvial soil
- Black soil
- Red soil
- Laterite soil
- Mountain soil
- Desert soil
Q12: What is soil erosion and how can it be prevented?
A12: Soil erosion is the removal or destruction of the top layer of soil by natural forces and human activities. It can be prevented through methods such as afforestation, controlled grazing, construction of dams, crop rotation, strip farming, contour ploughing, terrace farming, checking shifting cultivation, and wind breaks.
Q13: What is the literal meaning of lithosphere?
A13: The literal meaning of lithosphere is “The sphere of rock”.
Q14: What are extrusive igneous rocks and how are they formed?
A14: Extrusive igneous rocks are formed when molten magma (lava) cools and solidifies on the earth’s surface. They are fine-grained and glassy in nature due to rapid solidification.
Q15: What is an example of an extrusive igneous rock?
A15: Basalt, found in the north western part of peninsular India, is an example of an extrusive igneous rock.
Q16: What are the two types of intrusive igneous rocks?
A16: The two types of intrusive igneous rocks are:
- Plutonic rocks (formed deep inside the earth’s crust)
- Hypabyssal rocks (formed at shallow depths)
Q17: What are organic sedimentary rocks?
A17: Organic sedimentary rocks are formed as a result of the decomposition of dead plants and animals. They contain fossils. Examples include chalk, talc, dolomite, and limestone.
Q18: What causes thermal metamorphism?
A18: Thermal metamorphism is caused mainly by high temperature.
Q19: How is sandstone transformed into quartzite?
A19: Sandstone is transformed into quartzite through thermal metamorphism.
Q20: What is the soil profile?
A20: The soil profile is defined as the vertical section of the soil from the ground surface extending downwards.
Q21: Why is alluvial soil considered the most productive?
A21: Alluvial soil is considered the most productive because it is formed by the deposition of silt by running water in river valleys, flood plains, and coastal regions.
Q22: What makes red soil red in color?
A22: The presence of iron oxide makes red soil brown to red in color.
Q23: Why are laterite soils infertile?
A23: Laterite soils are infertile because they are formed by the process of leaching.
Q24: When is World Soil Day observed?
A24: World Soil Day is observed on 5th December every year.
Q25: How long does it typically take to form one cm of soil in a mild climate?
A25: In environments characterized by mild climate, it takes 200-400 years to form one cm of soil.
Q26: What is petrology and what does it study?
