Sixth Standard Science Quiz For Students

Oxygen is essential for respiration, which is the process by which living organisms take in oxygen and release carbon dioxide. During respiration, oxygen is used by cells to break down glucose and produce energy in the form of ATP. This energy is then used for various cellular processes, such as growth, repair, and movement. Without oxygen, respiration cannot occur, and cells would not be able to produce the energy they need to function properly. Therefore, oxygen is crucial for respiration.

The amount of air is greatest near the surface because the Earth's atmosphere is denser closer to the ground. This is due to the force of gravity, which pulls the air molecules towards the surface. As a result, there are more air molecules in a given volume of space near the surface compared to higher altitudes.

The layer of ozone absorbs UV rays. Ozone is a molecule made up of three oxygen atoms, and it is found in the Earth's stratosphere. It acts as a protective layer by absorbing most of the Sun's harmful ultraviolet (UV) radiation. UV rays can cause various health issues, including skin cancer, cataracts, and weakened immune system. Therefore, the presence of ozone in the atmosphere is crucial in preventing excessive UV radiation from reaching the Earth's surface.

The correct answer is 21%. This is because oxygen makes up approximately 21% of the Earth's atmosphere. The majority of the air we breathe is composed of nitrogen (about 78%), with trace amounts of other gases such as carbon dioxide and argon.

Air, water, and land are referred to as natural resources because they are elements of the Earth's environment that are not created by humans. These resources are essential for the survival and well-being of all living organisms. Air provides oxygen for breathing, water is necessary for hydration and various processes, and land is used for agriculture, housing, and other human activities. These resources are finite and need to be conserved and managed responsibly to ensure their availability for future generations.

The statement is true because it generally takes a significant amount of time for soil to develop into a thick layer. Soil formation is a slow process that involves the weathering of rocks, the decomposition of organic matter, and the accumulation of minerals and nutrients. These processes occur over long periods of time, often taking hundreds or even thousands of years, to create a substantial layer of soil.

The statement is false because land and soil are not the same things. Land refers to the surface of the Earth, including areas of water, while soil specifically refers to the upper layer of the Earth's crust that supports plant growth. While soil is a component of land, they are not interchangeable terms.

The statement is false because the water in the lake is not called groundwater. Groundwater refers to water that is stored underground in the spaces between rocks and soil. Lakes, on the other hand, are bodies of water that are formed on the surface due to various factors such as rainfall, rivers, or glaciers. While groundwater can contribute to the water in a lake through seepage or springs, it is not accurate to say that the water in the lake itself is called groundwater.

The correct answer is 78%. This is because nitrogen makes up approximately 78% of the Earth's atmosphere. It is the most abundant gas in the atmosphere and is essential for many biological processes.

The exosphere is the outermost layer of the Earth's atmosphere, extending from about 500 to 1,000 kilometers above the surface. It is a region where the density of gases is extremely low and the molecules are very far apart. As a result, the exosphere does not contain a significant amount of gases compared to the other layers of the atmosphere. Therefore, it can be said that gases are not found in the exosphere.