The element with highest ionization energy in the second period is:
A. Neon
B. Fluorine
C. Lithium
D. Beryllium
Answer: Option A
Solution (By JKSSB Mock Tests)
Ionization energy generally increases across a period due to increasing nuclear charge. Neon (noble gas) has the highest ionization energy in period 2 because of its stable filled octet (2s²2p⁶). Removing an electron requires enormous energy. Fluorine is next highest. Lithium has lowest. Noble gases have very high IE values, making them inert.
Explanation:
Boiling converts soluble bicarbonates of Ca and Mg to insoluble carbonates: Ca(HCO₃)₂ (heat) → CaCO₃↓ + H₂O + CO₂, which can then be filtered. Permanent hardness (due to sulfates/chlorides) is not removed by boiling; requires washing soda, ion exchange, or calgon. Calcium sulfate addition would increase permanent hardness. Filtration removes solid particles, not dissolved ions.
Explanation:
Chlorine acts as a disinfectant, killing bacteria, viruses, and other pathogens, making water safe for drinking. It forms hypochlorous acid (HOCl) in water which is a strong oxidizing agent. Sedimentation and filtration remove suspended particles. Taste may be affected if excess chlorine or by-products form. Chlorine residual protects water in distribution pipes.
Explanation:
On boiling, soluble calcium bicarbonate decomposes: Ca(HCO₃)₂ → CaCO₃↓ + H₂O + CO₂. The precipitate is calcium carbonate (limestone/chalk). Magnesium bicarbonate similarly forms MgCO₃ or Mg(OH)₂. This removes Ca²⁺ and Mg²⁺ ions, softening the water. Permanent hardness (CaSO₄, CaCl₂) doesn't precipitate on boiling and needs chemical treatment.
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