PVC (polyvinyl chloride) is used for making pipes and insulation because it is:
A. A good insulator and chemically resistant
B. Biodegradable
C. Highly flexible without additives
D. Conductor of electricity
Answer: Option A
Solution (By JKSSB Mock Tests)
PVC is a good electrical insulator, resistant to chemicals, water, and fire (self-extinguishing due to chlorine content), making it suitable for cable insulation, pipes, and medical tubing. It is not biodegradable. Flexibility is achieved by adding plasticizers, otherwise rigid. It is an addition polymer of vinyl chloride. Unplasticized PVC (uPVC) is used in construction.
Explanation:
Alpha particles, being heavy and doubly charged, cause intense ionization over a short distance. They are least penetrating. Gamma has low ionization but high penetration.
Explanation:
Temporary hardness is due to dissolved bicarbonates of Ca and Mg, which can be removed by boiling: Ca(HCO₃)₂ → CaCO₃↓ + H₂O + CO₂. Permanent hardness is caused by chlorides and sulfates of Ca and Mg, not removed by boiling. Sodium bicarbonate does not cause hardness. Methods to remove permanent hardness include treatment with washing soda (Na₂CO₃), ion exchange, or calgon.
Explanation:
John Dalton formulated the law of multiple proportions: If two elements can combine to form more than one compound, the masses of one element that combine with a fixed mass of the other are in ratios of small whole numbers. Lavoisier gave law of conservation of mass. Proust gave law of definite proportions. Dalton's atomic theory explained these laws.
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