Ozonation in water treatment is better than chlorination because it: MCQ with Answer and Explanation

Ozonation in water treatment is better than chlorination because it:
A. Is cheaper
B. Leaves no harmful residue
C. Is easier to store
D. Adds minerals
Answer: Option B
Solution (By JKExamLibrary)
Ozone decomposes to O₂, leaving no residual taste or toxic by-products like trihalomethanes. However, it must be generated on-site and is more expensive.

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Practice More chemistry Questions

Question #1
Soaps are sodium salts of long-chain fatty acids. Which part of soap dissolves in grease?
A. Sodium ion
B. Hydrocarbon tail
C. Water molecule
D. Ionic head

Correct Answer: Option B


Explanation:
The long non-polar hydrocarbon tail is hydrophobic and dissolves in grease/oil. The ionic head (carboxylate) is hydrophilic and interacts with water. This dual nature enables micelle formation and cleaning.

This question belongs to: Science chemistry
Question #2
Which of the following statements about a catalyst is incorrect?
A. It does not change the enthalpy of the reaction.
B. It remains unchanged in mass after the reaction.
C. It initiates the reaction.
D. It lowers the activation energy.

Correct Answer: Option C


Explanation:
A catalyst does not initiate a reaction; it only changes the rate of a reaction that is already thermodynamically feasible. It provides an alternative pathway with lower activation energy. It does not change the overall enthalpy (ΔH) or the equilibrium position, and it is recovered unchanged in mass.

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Question #3
The valency of phosphorus in PCl₅ is:
A. 5
B. 3
C. 6
D. 1

Correct Answer: Option A


Explanation:
In PCl₅, phosphorus forms five covalent bonds with five chlorine atoms. Phosphorus has 5 valence electrons (3s²3p³), and by using d-orbitals, it can expand its octet to accommodate 5 bonds. Thus its covalency is 5. In PCl₃, it is 3. Valency is the number of bonds formed. The oxidation state of P in PCl₅ is +5.

This question belongs to: Science chemistry