Question

Which of the following statements is not true? a. Water is polar. b. Water stabilizes temperature. C. Water is essential for life. d. Water is the most abundant atom in Earth's atmosphere.

Short answer

The statement 'Water is the most abundant atom in the Earth's atmosphere' is not true.

Step-by-step solution

Identify the properties of water

Water is known for being a polar molecule. This polarity is attributed to the difference in electronegativity between the oxygen atom and the hydrogen atom in water. This results in a net dipole moment. Therefore, statement 'a' is true.

Analyze the stabilizing role of water

Water has a high specific heat capacity, meaning it requires significantly more heat energy to increase its temperature. This unique property makes water excellent at stabilizing temperatures, especially in large bodies such as oceans, and in living organisms. Therefore, statement 'b' is true.

Study the essential role of water for life

Water is a fundamental substance for all biological systems. It is necessary for biochemical reactions, in transportation of substances in bodies of living organisms, and in thermoregulation. Therefore, statement 'c' is true.

Check abundance of water in Earth's atmosphere

Water, in the form of vapor, exists in the atmosphere, but is not the most abundant. Nitrogen (approximately 78%) and oxygen (approximately 21%) constitute most of the Earth's atmosphere, with the remaining 1% attributed to argon and other trace gases, including water vapor. Therefore, statement 'd' is not true.

Key concepts

Water Polarity

Water is an incredibly fascinating molecule, and one of its defining characteristics is polarity. This means that each water molecule has a positive and a negative end. Think of it like a tiny magnet. This happens because the oxygen atom and the hydrogen atom in the water molecule have different levels of electronegativity, which is the ability of an atom to attract electrons. The oxygen atom is more electronegative than the hydrogen atoms. As a result, the electrons tend to spend more time closer to the oxygen atom, giving it a slight negative charge, while the hydrogen atoms become slightly positive.
This polarity allows water molecules to form hydrogen bonds with each other and with other substances. This interaction is why water can effectively dissolve many different substances, earning it the title "universal solvent." Water's polarity is fundamental to many of its other unique properties. It allows water to interact and mix with various substances, which is beneficial in numerous biological and chemical processes.

Temperature Stabilization

Water plays a crucial role in stabilizing temperature, both in the environment and within living organisms. It has a remarkably high specific heat capacity, which means it can absorb a lot of heat before it begins to get hot. This property is due to the extensive hydrogen bonding between water molecules.
When heat is added to water, much of that energy is used to break the hydrogen bonds rather than increase the temperature. Because of this, water can absorb and store more heat energy compared to most other substances. This ability is instrumental in regulating Earth's climate by moderating day-night temperature fluctuations and providing a stable environment for marine life.
In biological systems, thermal regulation ensures that organisms maintain a stable internal temperature, which is vital for their survival. This is evident in both large bodies of water, like oceans, and smaller scale, such as in the sweating mechanism in humans.

Water in Atmosphere

Water is present in the atmosphere mainly in the form of water vapor, clouds, and precipitation. However, unlike some might think, it is not the most abundant component of the atmosphere. Nitrogen and oxygen are far more prevalent. Water vapor typically constitutes a small fraction of the atmospheric composition, varying from about 0 to 4% depending on various factors like temperature and humidity.
Although smaller in quantity, water vapor is essential as it plays a significant role in the Earth’s weather and climate system. It is responsible for phenomena such as cloud formation and precipitation. It also acts as a greenhouse gas, trapping heat and helping to regulate the planet’s temperature. Overall, while not the most abundant, water vapor is critical for life and environmental processes.

Biological Importance of Water

Water is indeed indispensable for life as we know it. Every living organism depends on water for their survival. It is involved in countless biochemical reactions. It's crucial for digesting food, transporting nutrients and waste products, and allowing for cellular processes.

• Component of Cells: About 60-70% of the human body is made up of water, which provides a medium for cellular reactions and contributes to the structure of cells.
• Dissolution and Transport: Water’s ability to dissolve a wide range of substances allows it to carry nutrients and waste products throughout an organism.
• Temperature Regulation: Water helps maintain a constant body temperature, critical for enzymatic activities necessary for survival.

For plants, water is critical in processes like photosynthesis, where it provides the hydrogen needed to build organic molecules. Additionally, its cohesive and adhesive properties help transport water from the roots to the leaves.