I. Select the Correct Option The gas released during respiration is: (b) carbon dioxide (During respiration, living organisms take in oxygen and release carbon dioxide as a waste product.) Acid rain is formed due to the contribution from the following pair of gases: (d) carbon dioxide and sulphur dioxide (Acid rain is primarily caused by the reaction of sulphur dioxide and nitrogen oxides with water in the atmosphere, though carbon dioxide also contributes to acidity.) Which gas is present in the highest abundance in the atmosphere? (c) Nitrogen (Nitrogen makes up approximately 78% of the Earth's atmosphere.) A gas is colourless, odourless, heavier than air, and extinguishes fire. Name the gas: (b) Carbon dioxide (Carbon dioxide is heavier than air and does not support combustion, making it useful in fire extinguishers.) Hot air balloon rises up in the air because: (b) hot air is lighter th...
I. Select the Correct Option: 1. The ratio of hydrogen and oxygen in water is: o (a) 2:1 Explanation: The chemical formula of water is H₂O, which means it contains two atoms of hydrogen and one atom of oxygen. 2. An element that kills living germs found in water is: o (b) chlorine Explanation: Chlorine is commonly used to disinfect water and kill harmful germs and bacteria. 3. The most impure water is: o (c) sea water Explanation: Sea water contains a high concentration of dissolved salts and minerals, making it unfit for drinking without treatment. 4. The hardness of water is due to the presence of: o (b) calcium and magnesium salts Explanation: Hard water contains dissolved salts of calcium and magnesium, which cause hardness. 5. Which of the following ...