Olympiad Test: Air And Water-1 - Class 6

The pH of pure water is 7. In general, water with a pH lower than 7 is considered acidic, and with a pH greater than 7 is considered basic. The normal range for pH in surface water systems is 6.5 to 8.5, and the pH range for groundwater systems is between 6 to 8.5.

Plants regulate the rate of transpiration by controlling the size of the stomatal apertures. The rate of transpiration is also influenced by the evaporative demand of the atmosphere surrounding the leaf such as boundary layer conductance, humidity, temperature, wind and incident sunlight.

During daylight, photosynthesis is the dominant process as a result amount of O 2 O_2 O2 released during day time is ten times greater than the amount of O 2 O_2 O2 utilized in day time. Because, respiration is more dominant in night time than day time

Explanation:
Given information:
- When water gains heat, it changes into water vapor.
- 1 cm³ of water forms more than 1000 cm³ of water vapor.
- The amount of particles (matter) in water remains the same.
Inferences:
Based on the given information, we can infer or conclude the following:
1. The spacing between the particles increases when water changes into water vapor:
- Water vapor occupies more volume than liquid water, indicating that the particles are spread out more in the vapor phase.
- The conversion of liquid water to water vapor involves the particles gaining energy and moving further apart from each other.
2. Water can exist in three interchangeable states:
- The information states that water changes from its liquid state to the vapor state when it gains heat.
- This suggests that water can exist in three states: solid (ice), liquid (water), and gas (water vapor).
- The ability of water to exist in these three states is due to its unique molecular structure and the presence of hydrogen bonding.
Therefore, the correct inference or conclusion from the given information is option B: 2 only.

Why pure and distilled water is not used for drinking:

1. Availability:

Pure and distilled water is not easily available for drinking purposes. It requires specific equipment and processes to obtain pure and distilled water, which are not commonly found in households or easily accessible.

2. Bacterial Contamination:

Contrary to common belief, pure and distilled water is not completely free from bacteria. While the distillation process does remove many impurities, including most bacteria and viruses, it is not foolproof. Some bacteria can survive the distillation process, and if the water is not stored properly, it can become contaminated.

3. High Solubility:

Pure water has a high solubility, meaning it can dissolve various substances easily. This can be problematic for drinking purposes as it can absorb minerals and other contaminants from the environment, which may not be suitable for consumption.

4. Lack of Essential Minerals:

Pure and distilled water lacks essential minerals that are beneficial for our health. These minerals are usually present in tap water or mineral water and provide important nutrients to our body.

5. Potential Toxicity:

While pure water itself is not poisonous, consuming large quantities of pure and distilled water over a prolonged period can disrupt the electrolyte balance in our bodies. This can lead to electrolyte imbalances and potentially cause health issues.

Considering these factors, it is recommended to drink filtered or tap water that meets the safety standards and contains essential minerals for overall health and well-being.

Saline solution for intravenous infusion. Saline, also known as saline solution, is a mixture of sodium chloride in water and has a number of uses in medicine. Applied to the affected area it is used to clean wounds, help remove contact lenses, and help with dry eyes. The medical use of saline began around 1831.

All the Plants Require Nitrogen for:


A. Transpiration:
- Nitrogen is not directly involved in the process of transpiration.
- Transpiration is the process by which plants lose water through their leaves, and it is primarily driven by factors such as temperature, humidity, and the presence of stomata.
B. Reproduction:
- Nitrogen is important for the reproductive processes of plants.
- It is involved in the production of proteins and nucleic acids, which are essential for the development of flowers, fruits, and seeds.
- Nitrogen deficiency can lead to poor flower and fruit development, ultimately affecting reproduction.
C. Photosynthesis:
- Nitrogen is crucial for photosynthesis, the process by which plants convert sunlight, water, and carbon dioxide into glucose and oxygen.
- Nitrogen is a key component of chlorophyll, the pigment responsible for capturing sunlight and converting it into chemical energy.
- Without sufficient nitrogen, plants may exhibit chlorosis (yellowing of leaves) and have reduced photosynthetic capacity.
D. Growth:
- Nitrogen is essential for plant growth and development.
- It is a major component of amino acids, which are the building blocks of proteins.
- Proteins are involved in various cellular processes and are essential for cell division, enzyme activity, and the synthesis of new tissues.
- Nitrogen deficiency can lead to stunted growth, reduced leaf size, and overall poor plant development.
To summarize, while nitrogen is not directly involved in transpiration, it plays a vital role in the reproductive processes, photosynthesis, and overall growth of plants.

Who am I?
Key Points:
- Present in the air
- Needed by the human body to produce energy
- Enters the lungs when breathing in

The answer to the question is Oxygen. Here's a detailed explanation:
Present in the air:
- Oxygen is one of the main components of the Earth's atmosphere.
- It makes up about 21% of the air we breathe.
Needed by the human body to produce energy:
- Oxygen is essential for cellular respiration, which is the process by which our cells produce energy.
- During respiration, oxygen is used to break down glucose and other molecules, releasing energy in the form of ATP.
Enters the lungs when breathing in:
- When we inhale, air enters our lungs through the respiratory system.
- The oxygen in the air diffuses into the bloodstream through the alveoli in the lungs, where it binds to hemoglobin in red blood cells.
- The oxygen-rich blood is then pumped to various parts of the body to provide energy.
Therefore, based on the given information, the correct answer is Oxygen (D).

Factors to keep constant for a fair test:

1. Size of the beaker: The size of the beaker can affect the heat distribution and therefore the time taken for the solution to reach boiling point. By keeping the size of the beaker constant, Abhilasha ensures that the heat distribution is consistent across all the solutions.

2. Amount of solution: The amount of solution in each beaker can affect the rate at which it heats up. By keeping the amount of solution constant, Abhilasha ensures that the heat is applied evenly to each solution, allowing for a fair comparison of the time taken to reach boiling point.

3. Starting temperature of the solution: The starting temperature of the solution can affect the time taken to reach boiling point. By keeping the starting temperature constant, Abhilasha eliminates the variable of initial temperature and focuses solely on the time taken for the solutions to boil.

4. Final temperature of the solution: The final temperature of the solution is not necessary to keep constant in order to carry out a fair test. The objective is to compare the time taken for the solutions to reach boiling point, and the final temperature may vary depending on the specific solution.

Therefore, to carry out a fair test in comparing the time taken for different solutions to reach boiling point, Abhilasha must keep the following factors constant: 1. Size of the beaker, 2. Amount of solution, and 3. Starting temperature of the solution. The final temperature of the solution does not need to be kept constant.

The water cycle
The water cycle, also known as the hydrological cycle, is the continuous movement of water on, above, and below the Earth's surface. It involves various processes such as evaporation, condensation, precipitation, and runoff.
About the water cycle
There are several statements given, and we need to determine which one is true. Let's analyze each option:
A: Rain drops falling into the sea contain salt
This statement is incorrect. Raindrops are formed through the process of condensation, where water vapor cools down and forms water droplets. During this process, the impurities such as salt are left behind, and the raindrops are relatively pure.
B: The energy for the water cycle comes from the sun
This statement is true. The sun is the primary source of energy for the water cycle. Solar radiation heats the Earth's surface, causing water to evaporate from oceans, lakes, and other bodies of water. This evaporation process is essential for the water cycle to occur.
C: Clouds are water in the gaseous state
This statement is partially true. Clouds are not entirely composed of water in the gaseous state. They consist of tiny water droplets or ice crystals suspended in the air. These particles condense around tiny dust or smoke particles to form visible clouds.
D: Water condenses to form water vapor
This statement is incorrect. Water vapor is the gaseous state of water, while condensation refers to the process of water vapor turning into liquid water. When water vapor cools down, it condenses into tiny water droplets or ice crystals, which can then form clouds or precipitation.
Conclusion
Out of the given options, the true statement about the water cycle is:
The energy for the water cycle comes from the sun (Option B). Solar radiation provides the necessary energy for evaporation, which is a crucial step in the water cycle.

Answer:
The correct answer is B: 1, 3, and 4.
When water freezes, it undergoes a phase change from a liquid state to a solid state. This results in several changes:
1. State: Water changes from a liquid state to a solid state when it freezes. The particles in the water arrange themselves in a more organized pattern, forming a crystal lattice structure.
2. Mass: The mass of the water remains the same when it freezes. Freezing is a physical change, and no new substances are formed, so the amount of matter (mass) remains constant.
3. Volume: The volume of water decreases when it freezes. As the water molecules arrange themselves into a crystal lattice structure, they become more closely packed together, resulting in a decrease in volume.
4. Temperature: The temperature of the water decreases when it freezes. Heat energy is released during the freezing process as the water molecules slow down and form the crystal lattice structure. This energy is transferred to the surroundings, causing a decrease in temperature.
In summary, when water freezes, its state changes from liquid to solid, its volume decreases, and its temperature decreases. The mass of the water remains the same.

Explanation:
The water vapor in the air is primarily due to the processes of evaporation and transpiration. Here is a detailed explanation of each source of water vapor:
Evaporation from Oceans, Rivers, Lakes, and Streams:
- Water bodies such as oceans, rivers, lakes, and streams contain large amounts of water.
- Due to the heat from the sun, the water molecules gain energy and turn into water vapor.
- This process is known as evaporation, and it is a major source of water vapor in the air.
Transpiration from Plants:
- Plants have tiny openings called stomata on their leaves.
- Through these stomata, plants release water vapor into the air.
- This process is known as transpiration and is an essential part of a plant's life cycle.
- Transpiration accounts for a significant amount of water vapor in the atmosphere.
Sweat Evaporation:
- Animals, including humans, produce sweat as a way to cool down their bodies.
- When sweat evaporates from the skin's surface, it turns into water vapor.
- This adds a small amount of water vapor to the air.
Conclusion:
In conclusion, the water vapor in the air is due to the combined effects of evaporation from water bodies, transpiration from plants, and sweat evaporation from animals. Therefore, the correct answer is option D - All of the above.

Hard water, water that contains salts of calcium and magnesium principally as bicarbonates, chlorides, and sulfates. Water hardness that is caused by calcium bicarbonate is known as temporary, because boiling converts the bicarbonate to the insoluble carbonate; hardness from the other salts is called permanent.