Assertion (A): Boiling water removes temporary hardness. Reason (R): Boiling converts soluble bicarbonates into insoluble carbonates.
A. A is true but R is false.
B. A is false but R is true.
C. Both A and R are true but R is NOT the correct explanation of A.
D. Both A and R are true and R is the correct explanation of A.
Answer: Option D
Solution (By JKExamLibrary)
Temporary hardness is due to Ca(HCO₃)₂ and Mg(HCO₃)₂. Upon boiling, these decompose into insoluble CaCO₃ and Mg(OH)₂, which precipitate out and can be filtered. Thus, boiling effectively removes temporary hardness, and R correctly explains the chemical mechanism involved.
Explanation:
Iodine directly converts from solid to violet vapor on gentle heating (sublimation). NaCl melts; sugar decomposes; copper melts at high temperature. Other sublimable substances: camphor, naphthalene, dry ice.
Explanation:
Acid rain is formed when sulfur dioxide (SO₂) and nitrogen oxides (NOx) emitted into the atmosphere (from burning fossil fuels) react with water, oxygen, and other chemicals to form sulfuric and nitric acids. These acids then fall to the ground as rain, damaging ecosystems.
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