In electroplating of copper on an iron spoon, the electrolyte used is: MCQ with Answer and Explanation

Explanation:
Hard water contains dissolved Ca²⁺ and Mg²⁺ ions which react with soap to form insoluble scum, preventing lather. Soft water lathers readily. Distilled water is pure (soft). Rainwater is naturally soft but may dissolve CO₂ and become slightly acidic.

Explanation:
Enzymes are biological catalysts that function optimally at moderate temperatures (around 35-40°C for human enzymes). Most enzymes denature and lose activity at temperatures above 50-60°C, as the protein structure unfolds. They are highly specific (lock-and-key model), protein in nature, and lower activation energy without being consumed. Some thermophilic bacteria have enzymes active at high temperatures, but typical enzymes are not stable at >100°C.

Explanation:
Atomic radius increases down a group as the number of shells increases. Iodine (I) is in Period 5, below F (2), Cl (3), Br (4). Thus iodine has the largest atomic radius among these halogens.