The hardness of water that cannot be removed by boiling is called:
A. Softness
B. Temporary hardness
C. Alkalinity
D. Permanent hardness
Answer: Option D
Solution (By JKExamLibrary)
Permanent hardness is due to dissolved sulfates and chlorides of calcium and magnesium. Boiling does not remove it. It requires chemical treatment (washing soda, ion exchange) or distillation. Temporary hardness (bicarbonates) is removed by boiling.
Explanation:
CO₂ is a major greenhouse gas that absorbs infrared radiation and re-emits it, warming the atmosphere. Other GHGs: CH₄, N₂O, water vapor, CFCs. N₂ and O₂ are diatomic homonuclear molecules that do not absorb IR and are not GHGs. Hydrogen is not a GHG. The increase in CO₂ due to human activities is driving climate change.
Explanation:
Alumina has a very high melting point (~2050°C). Cryolite (and fluorspar) is mixed to form a molten mixture with lower melting point (~950°C) and better electrical conductivity, enabling electrolytic reduction. The electrolyte is a solution of alumina in molten cryolite. Carbon anodes are consumed. This reduces energy consumption.
Explanation:
Boyle's law: P ∝ 1/V or PV = constant at constant T and n. So if volume increases, pressure decreases. This is because gas molecules have more space and hit the walls less frequently. An example is a syringe: pulling the plunger increases volume, decreases pressure.
No comments yet. Be the first to start the discussion!