krit.club logo

Health: The Ultimate Treasure - Keep the environment clean

Grade 8CBSE

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

🔑Concepts

•

Health is a state of complete physical, mental, and social well-being, and not merely the absence of disease. It is deeply connected to the environment we live in.

•

Biodegradable Waste: Materials that can be decomposed by microorganisms (like bacteria and fungi) into simple substances. Examples include fruit peels, paper, and animal dung.

•

Non-biodegradable Waste: Materials that cannot be broken down by biological processes. Examples include plastics, glass, and chemicals like DDTDDT.

•

Pathogens: Disease-causing microorganisms such as bacteria, viruses, and protozoa that can spread through contaminated H2OH_{2}O or air.

•

Air Pollution: The presence of harmful substances like COCO, SO2SO_{2}, and NO2NO_{2} in the atmosphere which can cause respiratory diseases.

•

Acid Rain: Formed when SO2SO_{2} and NO2NO_{2} react with water vapor in the atmosphere to form sulfuric acid (H2SO4H_{2}SO_{4}) and nitric acid (HNO3HNO_{3}), leading to a pH lower than 5.65.6.

•

Water Purification: Making water potable using methods like boiling, chlorination (adding Cl2Cl_{2} tablets), and filtration to remove pathogens.

•

The 5R Principle for Waste Management: Refuse, Reduce, Reuse, Repurpose, and Recycle.

📐Formulae

6CO2+6H2O→sunlight/chlorophyllC6H12O6+6O26CO_{2} + 6H_{2}O \xrightarrow{\text{sunlight/chlorophyll}} C_{6}H_{12}O_{6} + 6O_{2}

Acid Rain Formation: SO2+H2O→H2SO3\text{Acid Rain Formation: } SO_{2} + H_{2}O \rightarrow H_{2}SO_{3}

General pH of pure water: pH=7\text{General pH of pure water: } pH = 7

💡Examples

Problem 1:

A housing society generates 8,5008,500 kg of total waste in a month. Out of this, 3,2503,250 kg is non-biodegradable plastic waste. Calculate the amount of biodegradable waste generated by the society using vertical subtraction.

Solution:

8500−32505250\begin{array}{r} 8500 \\ -3250 \\ \hline 5250 \end{array}

Explanation:

The total waste is the sum of biodegradable and non-biodegradable waste. By subtracting the non-biodegradable amount (3,2503,250 kg) from the total amount (8,5008,500 kg), we find that the society generates 5,2505,250 kg of biodegradable waste.

Problem 2:

If the concentration of a pollutant in a water body is 0.050.05 mg/L and the safety limit is 0.010.01 mg/L, by how many times does the pollutant exceed the safety limit?

Solution:

0.050.01=5\frac{0.05}{0.01} = 5

Explanation:

To find how many times the pollutant exceeds the limit, we divide the current concentration (0.050.05 mg/L) by the safe threshold (0.010.01 mg/L). The result is 55 times the safe limit.