Sodium hydroxide turns red litmus blue because it is: MCQ with Answer and Explanation

Sodium hydroxide turns red litmus blue because it is:
A. Acidic
B. Salty
C. Basic
D. Neutral
Answer: Option C
Solution (By JKExamLibrary)
NaOH is a strong base; it dissociates to give OH⁻ ions, making the solution basic (pH >7). Bases turn red litmus blue. Acids turn blue litmus red.

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Practice More chemistry Questions

Question #1
Which of the following methods is used to obtain pure copper from impure copper?
A. Smelting
B. Electrolytic refining
C. Calcination
D. Roasting

Correct Answer: Option B


Explanation:
In electrolytic refining, impure copper is the anode, pure copper is the cathode, and CuSO₄ acidified with H₂SO₄ is the electrolyte. Copper dissolves from anode and pure copper deposits on cathode. Smelting is reduction with coke.

This question belongs to: Science chemistry
Question #2
Which of the following molecules has a double covalent bond?
A. H₂
B. N₂
C. O₂
D. Cl₂

Correct Answer: Option C


Explanation:
In an oxygen molecule (O₂), each oxygen atom has 6 valence electrons and needs 2 more to complete its octet. They share two pairs of electrons, forming a double covalent bond (O=O). H₂ and Cl₂ have single bonds, while N₂ has a triple covalent bond (N≡N).

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Question #3
Which of the following is the strongest oxidizing agent based on standard reduction potentials?
A. Li+ (E° = -3.05 V)
B. Zn2+ (E° = -0.76 V)
C. F2 (E° = +2.87 V)
D. Cu2+ (E° = +0.34 V)

Correct Answer: Option C


Explanation:
The standard reduction potential (E°) indicates the tendency of a species to gain electrons. A higher positive E° value means a greater tendency to be reduced, making it a stronger oxidizing agent. Fluorine (F2) has the highest standard reduction potential (+2.87 V), making it the strongest oxidizing agent among the choices.

This question belongs to: Science chemistry