Which gas is evolved when sodium bicarbonate is heated?
A. Nitrogen
B. Oxygen
C. Carbon dioxide
D. Hydrogen
Answer: Option C
Solution (By JKExamLibrary)
2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O. Carbon dioxide is released, which turns limewater milky. This is a test for bicarbonates. Oxygen is not produced; hydrogen would need a reducing agent.
Explanation:
Chlorination is a disinfection process. Chlorine reacts with water to form hypochlorous acid, which kills bacteria and viruses. It also provides residual protection in distribution pipes. Filtration removes particles; chlorine does not remove dissolved minerals or improve taste significantly; it can cause taste issues if excess.
Explanation:
Bakelite is a thermosetting plastic, heat resistant and electrical insulator. Polythene and PVC are thermoplastics; they soften on heating. Teflon is non-stick.
Explanation:
Magnesium loses two electrons to achieve noble gas configuration (Mg → Mg²⁺), so its electrovalency is +2. In MgCl₂, Mg²⁺ and two Cl⁻. Electrovalency is the charge on the ion. Covalency is number of covalent bonds. For Group 2 metals, electrovalency is always +2 (loss of 2 electrons).
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