Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Water is essential for life, but natural water sources like rivers and ponds contain impurities. Pure water is represented by the chemical formula .
Impurities are classified into two types: Insoluble impurities (sand, mud) and Soluble impurities (salts).
Sedimentation: The process where heavy, insoluble impurities settle down at the bottom of a container when water is left undisturbed.
Decantation: The process of pouring out the clear water from the top into another container after sedimentation, without disturbing the settled particles.
Filtration: A process used to remove fine insoluble impurities by passing water through a filter, such as a fine cloth or filter paper.
Boiling: The simplest method to kill germs and bacteria. Water should be boiled at its boiling point of for at least 10-15 minutes.
Chlorination: Adding chlorine () tablets or bleaching powder to water to kill harmful microorganisms and make it safe for drinking.
📐Formulae
💡Examples
Problem 1:
During an experiment, a student mixes of sand in a beaker of water. Which physical process will help the sand settle at the bottom?
Solution:
Sedimentation
Explanation:
Sand is an insoluble impurity and is heavier than water. Due to gravity, the sand particles settle at the bottom of the beaker over time.
Problem 2:
Why is it recommended to heat to before drinking it during the monsoon season?
Solution:
To kill disease-causing germs.
Explanation:
Boiling water at ensures that most bacteria and viruses present in the water are destroyed, making it biologically safe for consumption.