What percentage of the Earth's water is freshwater?

Only 3% of the Earth's water is freshwater.

Fill in the blank: Water is considered a universal ___ because it can dissolve a wide variety of substances.

Solvent

True or False: Hard water contains a high concentration of sodium.

False. Hard water contains minerals like magnesium and calcium, not sodium.

What happens to the density of water as it cools down to 4°C?

The density of water is maximum at 4°C.

List two major sources of freshwater as mentioned.

Glaciers and groundwater.

Fill in the blank: Water pollution can cause diseases such as ___ and ___ due to contaminated sources.

Hepatitis and cholera

What is the process by which water vapor turns back into liquid called?

Condensation

True or False: Boiling water requires an external heat source while evaporation does not.

True

What method did Gandhiji use to protest against salt laws, and why was it significant?

He went on the Dandi March to make salt to protest against the law that prohibited Indians from making their own salt.

Fill in the blank: The saltiest body of water is the ___ Sea.

Dead

Name one human activity that contributes to water pollution.

Discharging untreated sewage into water bodies.

What is the significance of using alum in water purification?

Alum helps in settling impurities at the bottom of the water to make it safe for drinking.

Riddle: I keep your skin soft but can be harmful when hard. What am I?

Soft water