Test: Natural Resource Water And Soil - Class 9 MCQ

175 million hectares of land area suffer from degradation. Land degradation is caused largely by soil erosion but also by water logging and excessive salinity. The high degree of degradation will affect the existing land resources.

Explanation:
The incorrect statement is:
D: Our body does not need to maintain the level of water within their bodies.
Here is a detailed explanation of why this statement is incorrect:
- Water is essential for the functioning of our body and is involved in various cellular processes. Therefore, it is crucial to maintain the level of water within our bodies.
- Our body is made up of approximately 60% water, and it plays a vital role in many physiological functions.
- Water acts as a solvent, facilitating chemical reactions and the transportation of substances within our body.
- Water helps regulate body temperature through sweating and evaporation.
- It is involved in the digestion and absorption of nutrients, as well as the elimination of waste products through urine and feces.
- Adequate hydration is necessary for maintaining proper organ function, lubricating joints, and supporting overall health.
- Dehydration can lead to various health problems, including fatigue, dizziness, kidney stones, and even life-threatening conditions in severe cases.
Therefore, it is incorrect to state that our body does not need to maintain the level of water within their bodies. Water is essential for our overall well-being and the proper functioning of our cells and organs.

Breaking down bigger rocks into fine smaller mineral particles is a natural process known as weathering. Weathering is a key part of the rock cycle and plays a crucial role in shaping the Earth's surface. Here is a detailed explanation of weathering:
Weathering:
Weathering is the process by which rocks are broken down into smaller particles through various physical and chemical processes. It is a fundamental process that occurs over time and is influenced by factors such as temperature, moisture, and the presence of certain minerals.
Types of Weathering:
There are two main types of weathering:
1. Mechanical Weathering:
- Also known as physical weathering, it involves the physical breakdown of rocks into smaller fragments without any change in their chemical composition.
- Mechanical weathering processes include freeze-thaw cycles, abrasion by wind and water, and root wedging.
2. Chemical Weathering:
- Chemical weathering involves the alteration of rocks through chemical reactions, resulting in the breakdown of minerals and the formation of new compounds.
- Common chemical weathering processes include hydrolysis, oxidation, and carbonation.
Significance of Weathering:
Weathering plays a crucial role in the formation of soil and the release of essential nutrients for plant growth. It also contributes to the erosion and transport of sediments, which can lead to the formation of new landforms. Additionally, weathering can affect the stability of structures and impact human activities, such as agriculture and construction.
In conclusion, the breakdown of bigger rocks into fine smaller mineral particles is known as weathering. This natural process occurs through mechanical and chemical processes and is essential in shaping the Earth's surface.

Good topsoil should be nutrient and mineral rich and promote the growth of plants in your lawn or garden. Topsoil is the layer on top of the subsoil, and it sometimes differs because it has a high amount of organic matter, is nutrient rich, and has low salts.

Function of Humus:
Humus is a crucial component of soil that is formed by the decomposition of organic matter. It plays several important roles in supporting healthy soil and plant growth. However, one function that humus does not perform is killing harmful bacteria present in the soil.
Here are the functions of humus:
1. Enhances water and air penetration:
- Humus helps to improve soil structure by binding soil particles together.
- It creates pore spaces in the soil, allowing water and air to penetrate deep underground.
- This promotes better drainage and aeration, which are essential for root growth and nutrient availability.
2. Influences soil structure:
- Humus greatly influences the soil structure of a region by improving its texture.
- It helps to stabilize soil aggregates, preventing erosion and compaction.
- This allows for better root development and nutrient uptake.
3. Increases soil porosity:
- Humus causes the soil to become more porous, creating a favorable environment for soil organisms.
- Increased soil porosity allows for better water infiltration and root penetration.
4. Nutrient retention and release:
- Humus acts as a reservoir for essential plant nutrients, such as nitrogen, phosphorus, and potassium.
- It has the ability to retain and slowly release these nutrients, providing a steady supply to plants.
5. Improves soil fertility:
- Humus enhances soil fertility by improving nutrient availability and soil structure.
- It promotes microbial activity, which aids in organic matter decomposition and nutrient cycling.
Conclusion:
In conclusion, while humus performs several important functions in soil, it does not kill harmful bacteria present in the soil. It is essential to maintain a balance of beneficial soil microorganisms for healthy soil ecosystems.

Dissolved oxygen in water body b... moreecause oxygen is pure gas it is safe and pure for living beings to intake as we know that human beings breathes in oxygen and release carbon dioxide so this implies oxygen is a pure gas and not dangerous for anything even not for water.

Approximately 70 percent of the earth is covered by water. Of this amount, approximately ____ percent of it is suitable for human use.
To find the percentage of water suitable for human use, we need to consider the following:
Step 1: Calculate the total percentage of water on earth.
- Given that approximately 70 percent of the earth is covered by water.
Step 2: Determine the percentage of water suitable for human use.
- This percentage will be less than the total percentage of water on earth.

- Total percentage of water on earth: 70 percent
Now, let's consider the percentage of water suitable for human use. It is important to note that not all water is suitable for human consumption due to factors such as salinity, pollution, and inaccessibility. The suitable percentage of water is significantly lower than the total percentage of water on earth.
Therefore, the correct answer is D: less than one percent.

In general, it is hard to see vegetation over 2000 meters above mean sea level. Therefore soil erosion occurs in high mountains due to ice melting, rainfall, wind.

Cotton plants tend to do well in deep, well-drained, and highly fertile sandy loam soils with a pH between 5.5 & 7.5 – Cotton plants are vulnerable to the aluminum concentration often found in soils with a pH below that range.

Ground water is not source of pure water because when rain water(fresh water) come in contact with ground it combined with ground mineral and became impure.