Test: Waste Water Story - Class 7 MCQ

The process of waste treatment is called as sewage treatment to remove harmful substance from water to make it portable.

• Pollution: Contaminates water sources, making them unsafe for use and further reducing available freshwater.
• Industrial Development: Increases water consumption and often leads to pollution, straining freshwater resources.
• Population Growth: More people result in higher water demand for personal, agricultural, and industrial use.

All these factors contribute to the scarcity of freshwater, making option D: All of the above the correct answer. 

Biodegradable wastes are generally organic in nature obtained from plant and animals.

Bar screens are used to remove large objects like rags, sticks, cans, and plastic packets from wastewater as it passes through them.

Sewage is wastewater released by homes, industries, hospitals, offices and other users. It also includes rainwater that has run down the street during a storm or heavy rain. The water that washes off roads and rooftops carries harmful substances with it. Sewage is a liquid waste. Most of it is water, which has dissolved and suspended impurities.

Vegetable peels, cotton cloths and paper are plant products and organic wastes while DDT is manmade inorganic substance used as pesticides.

• Inorganic Impurities: These are non-living, chemical substances found in sewage.
• Phosphate: A common inorganic impurity present in sewage. It comes from detergents, fertilizers, and industrial waste.
• Garbage and Vegetable Waste: These are organic impurities as they originate from living organisms or their processes.
  Correct Answer: C. Phosphate is inorganic because it consists of a mineral component, unlike organic waste from biological origins.

Drains get blocked by a combination of substances, leading to clogs. The correct answer is C: All of these. Here's why:

- Hair: Accumulates in drains, combining with other substances.
- Soap: Residue can solidify, trapping debris.
- Cooking oil and fats: Harden over time, narrowing drain passages.

By choosing option C, you acknowledge that all these factors contribute to drain blockages, emphasizing the importance of regular maintenance to prevent clogs effectively.