Chlorine is used in water treatment primarily to: MCQ with Answer and Explanation

Chlorine is used in water treatment primarily to:
A. Remove suspended particles
B. Kill pathogenic microorganisms
C. Add minerals
D. Improve taste
Answer: Option B
Solution (By JKSSB Mock Tests)
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.

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Practice More chemistry Questions

Question #1
Assertion (A): The first ionization energy of Nitrogen is higher than that of Oxygen. Reason (R): Nitrogen has a half-filled p-orbital which is exceptionally stable.
A. A is false but R is true.
B. A is true but R is false.
C. Both A and R are true and R is the correct explanation of A.
D. Both A and R are true but R is NOT the correct explanation of A.

Correct Answer: Option C


Explanation:
Nitrogen (1s2 2s2 2p3) has a exactly half-filled p-subshell, which confers extra stability due to symmetry and exchange energy. Oxygen (1s2 2s2 2p4) has one paired electron in the p-orbital, leading to electron-electron repulsion, making it easier to remove. Thus, N has a higher IE than O. Both are true and R explains A.

This question belongs to: Science chemistry
Question #2
The equivalent weight of KMnO4 in an acidic medium is:
A. M/1
B. M/5
C. M/3
D. M/7

Correct Answer: Option B


Explanation:
In an acidic medium, potassium permanganate (KMnO4) is reduced to Mn2+. The oxidation state of Mn changes from +7 to +2, a change of 5. The equivalent weight of an oxidizing agent is its molar mass (M) divided by the number of electrons gained per molecule. Thus, Equivalent weight = M/5.

This question belongs to: Science chemistry
Question #3
The pH of pure water at 25°C is 7. This is because:
A. It contains equal concentrations of H⁺ and OH⁻ ions
B. It has no ions
C. It contains only OH⁻
D. It is a strong acid

Correct Answer: Option A


Explanation:
Water self-ionizes: H₂O ⇌ H⁺ + OH⁻. At 25°C, [H⁺] = [OH⁻] = 10⁻⁷ mol/L, so Kw = 10⁻¹⁴ and pH = pOH = 7. A solution is neutral when [H⁺] = [OH⁻]. pH 7 is neutral only at 25°C; at higher temperatures, Kw increases, pH of neutrality drops but still [H⁺]=[OH⁻].

This question belongs to: Science chemistry