Which of the following is a chemical change? MCQ with Answer and Explanation

Explanation:
In electrolysis, the external power source forces non-spontaneous reactions. Electrons are drawn away from the anode, making it positive. Thus anode is connected to the positive terminal. In a galvanic (voltaic) cell, anode is negative. Remember: electrolytic cell – anode positive; oxidation still occurs at anode. Electroplating uses this setup: object to be plated is cathode, source metal is anode.

Explanation:
Methane undergoes substitution reaction with chlorine in UV light: CH₄ + Cl₂ → CH₃Cl + HCl. Further substitution can give CH₂Cl₂, CHCl₃, CCl₄. This is a free radical mechanism. It does not produce methanol or ethane.

Explanation:
Methanol (CH₃OH) is metabolized to formaldehyde and formic acid, causing optic nerve damage, blindness, or death. Ethanol is used in beverages.