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Water - Importance of Water

Grade 6ICSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Water is a vital natural resource essential for all forms of life. It is a chemical compound composed of two atoms of Hydrogen and one atom of Oxygen, represented as H2OH_2O.

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Water is known as the 'Universal Solvent' because it has the unique ability to dissolve more substances than any other liquid.

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Water exists in three states of matter: Solid (ice), Liquid (water), and Gas (water vapor). These states are interconvertible through processes like melting, evaporation, condensation, and freezing.

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About 70%70\% of the human body weight is made up of water. It helps in the digestion of food, transport of nutrients, and regulation of body temperature through sweating.

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In plants, water is essential for the process of photosynthesis, where they prepare food using sunlight, CO2CO_2, and water. It also helps in the germination of seeds.

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The 'Water Cycle' is the continuous movement of water between the Earth's surface and the atmosphere through evaporation, transpiration, condensation, and precipitation.

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The physical properties of pure water include being colorless, odorless, and tasteless, with a freezing point of 0∘C0^\circ C and a boiling point of 100∘C100^\circ C at sea level.

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Potable water is water that is safe for drinking and human consumption, free from harmful germs and impurities.

📐Formulae

H2OH_2O

Freezing Point of Water=0∘C\text{Freezing Point of Water} = 0^\circ C

Boiling Point of Water=100∘C\text{Boiling Point of Water} = 100^\circ C

6CO2+6H2O→sunlightC6H12O6+6O26CO_2 + 6H_2O \xrightarrow{\text{sunlight}} C_6H_{12}O_6 + 6O_2

💡Examples

Problem 1:

If a student has a total body mass of 40 kg40\text{ kg}, approximately how much of that mass is water?

Solution:

40 kg×70100=28 kg40\text{ kg} \times \frac{70}{100} = 28\text{ kg}

Explanation:

Since approximately 70%70\% of the human body weight is composed of water, we multiply the total mass by 0.700.70 to find the mass of water in the body.

Problem 2:

Identify the process: Water vapor (gas)→(\text{gas}) \rightarrow Water (liquid)(\text{liquid}).

Solution:

Condensation

Explanation:

Condensation is the process by which water vapor in the air is changed into liquid water when it cools down.

Problem 3:

Why does a drop of ink spread when added to a beaker of water?

Solution:

Due to the property of water as a solvent and the process of diffusion.

Explanation:

Water acts as a solvent that allows the solute (ink) particles to move freely between the H2OH_2O molecules until the mixture is uniform.