Assertion (A): Zinc can displace copper from copper sulfate solution. Reason (R): Zinc is more reactive than copper.
A. Both A and R are true but R is NOT the correct explanation of A.
B. A is true but R is false.
C. A is false but R is true.
D. Both A and R are true and R is the correct explanation of A.
Answer: Option D
Solution (By JKSSB Mock Tests)
In the electrochemical series, zinc is placed above copper, meaning it has a higher oxidation potential (is more reactive). A more reactive metal can displace a less reactive metal from its aqueous salt solution. Therefore, zinc displaces copper from CuSO4, forming ZnSO4 and depositing Cu metal. R correctly explains A.
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:
Phenolphthalein is colorless in acidic and neutral solutions, turning pink/magenta in basic solutions with pH > about 8.2-10. It is commonly used in acid-base titrations. Methyl orange is red in acidic and yellow in basic. Litmus is purple in neutral, red in acid, blue in base. Natural indicators like turmeric, beetroot also show color changes.
Explanation:
A lead-acid battery, commonly used in automobiles, consists of lead anodes and lead dioxide cathodes. The electrolyte used is an aqueous solution of sulfuric acid (H2SO4). During discharge, the acid is consumed to form lead sulfate and water, decreasing the density of the electrolyte.
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