Olympiad Test : Water - 2 - Class 5 MCQ

When salt, sugar, vinegar, lemon juice, and soda are added to water, most of these ingredients dissolve in the water (salt and sugar are soluble). The soda may create bubbles, but overall, the mixture forms a homogeneous, soluble mixture where most ingredients mix with the water.

The image likely depicts a water pump, which is a device used to move water from one place to another, often used in irrigation or water supply systems. It helps in drawing water from wells, rivers, or other sources.

Water's high surface tension gives it several unique properties:

• A: It allows water to bead on objects, like droplets forming on a glass surface.
• B: It gives water a sticky property, helping it adhere to surfaces.
• C: It helps water circulate upward on and through objects, such as in capillary action, where water rises through narrow tubes like plant stems.

So, all these properties are a result of water's high surface tension.

The latent heat of fusion for water is approximately 80 calories. This means that when 1 gram of ice melts into water at 273 K (0°C), it absorbs 80 calories of energy. Conversely, when 1 gram of water freezes to form ice, it releases 80 calories of energy.

So the correct answer should be: C: 80

During a phase change (like from solid to liquid or liquid to gas), the energy that is added to the water is used to overcome the forces holding the water molecules together (such as hydrogen bonds), rather than increasing the temperature. This energy is called latent heat. As a result, the temperature remains constant while the phase change occurs.

When water vapor condenses into liquid water, energy is released into the surrounding atmosphere. This release of energy warms the surrounding air, which is why condensation often leads to a rise in temperature in the environment.

The greatest significance of latent heat is that it allows water vapor to store and release large amounts of heat. When water vapor condenses into liquid water, it releases latent heat, which warms the surrounding atmosphere. This is crucial in weather systems, such as during the formation of clouds and storms, as it helps drive atmospheric circulation and influences the Earth's climate.

Solubility is the property that describes how much of a solute can dissolve in a solvent to form a homogeneous solution at a given temperature and pressure. It indicates how easily a substance can be dissolved in a liquid.

Aquatic plants, which grow in or near water, are known as hydrophytes. They are specially adapted to thrive in water-rich environments, with features like air spaces in their tissues or roots that can survive submerged conditions.

Sugar and salt are soluble in water, meaning they dissolve completely when added to water. However, chalk powder and sawdust do not dissolve in water, they either form a suspension or remain undissolved.

Insoluble impurities in water can be removed through sedimentation, a process where solid particles settle at the bottom of a container due to gravity. This occurs when the water is left undisturbed, allowing heavier particles to separate from the water. After sedimentation, the clear water can be decanted or filtered for further purification.

Filtration is the process by which an insoluble impurity is separated from a liquid by passing the mixture through filter paper. The filter paper allows the liquid to pass through while trapping the solid particles, effectively separating the impurities from the liquid.

Distilled water is the purest form of water, as it is obtained by boiling water to produce steam and then condensing the steam back into liquid form. This process removes impurities, minerals, and contaminants. Distilled water is commonly used in car batteries to prevent mineral buildup and maintain proper function.

The Dead Sea is the saltiest water body in the world, with a salt concentration of around 30%. This makes it much saltier than other seas or oceans. Its high salinity prevents most marine life from thriving, which is why it is called the "Dead Sea."

The best time to water your lawn is in the early morning, between 6 a.m. and 10 a.m. This timing allows the water to soak into the soil before the heat of the day causes evaporation. Watering in the evening can also be effective but should be done early enough to avoid prolonged moisture on the grass overnight, which can lead to lawn diseases.