Which layer of soil contains the most organic matter and nutrients?

• Bedrock

• Topsoil

• Subsoil

• Parent material

Answer explanation

Topsoil is the uppermost layer of soil and is rich in organic matter and nutrients, making it essential for plant growth. In contrast, bedrock, subsoil, and parent material contain fewer nutrients and organic materials.

What is the primary cause of soil degradation worldwide?

• Natural disasters

• Poor farming practices

• Animal activity

• Temperature changes

Answer explanation

Poor farming practices, such as overgrazing, monoculture, and excessive use of chemicals, lead to soil degradation by depleting nutrients and harming soil structure, making it the primary cause of this global issue.

Which of these is an example of a luminous object?

• Moon

• Stars

• Planets

• Clouds

Answer explanation

Stars are luminous objects because they generate their own light through nuclear fusion. In contrast, the Moon and planets reflect light from the Sun, and clouds do not emit light, making stars the correct choice.

What term describes the average weather conditions in an area over a long period?

• Forecast

• Season

• Weather

• Climate

Answer explanation

The term 'climate' refers to the average weather conditions in an area over a long period, distinguishing it from 'weather,' which describes short-term atmospheric conditions.

Which soil type is best for growing most plants?

• Clay soil

• Sandy soil

• Loam soil

• Silt soil

Answer explanation

Loam soil is considered the best for growing most plants because it has a balanced mixture of sand, silt, and clay, providing good drainage, nutrient retention, and aeration, which are essential for healthy plant growth.

What is a major human activity that contributes to air pollution?

• Walking

• Factory emissions

• Reading

• Gardening

Answer explanation

Factory emissions are a significant source of air pollution, releasing harmful pollutants into the atmosphere. In contrast, activities like walking, reading, and gardening do not contribute to air pollution.

Which environment type is characterized by low rainfall and extreme temperatures?

• Tundra

• Rainforest

• Desert

• Grassland

Answer explanation

Deserts are characterized by low rainfall and extreme temperatures, often experiencing very hot days and cold nights. This makes 'Desert' the correct answer, unlike tundras, rainforests, and grasslands which have different climate conditions.

What is the main difference between weather and climate?

• Weather describes long-term patterns

• Climate describes daily conditions

• Weather describes short-term conditions

• They are exactly the same

Answer explanation

The main difference is that weather describes short-term conditions, such as daily temperature and precipitation, while climate refers to long-term patterns and averages over extended periods.

Which of these is NOT a non-luminous object?

• The Sun

• A book

• A mirror

• A wall

Answer explanation

The Sun is a luminous object because it produces its own light. In contrast, a book, a mirror, and a wall do not emit light; they reflect or absorb it, making them non-luminous.

What causes soil erosion?

• Tree planting

• Wind and water

• Composting

• Crop rotation

Answer explanation

Soil erosion is primarily caused by natural forces like wind and water, which can displace soil particles. Tree planting, composting, and crop rotation help prevent erosion but do not cause it.