Identifying the incorrect statement on electrical conductivity mechanisms

Steps:

• Recall that electrical conductivity requires mobile charged particles: ions in electrolytes or electrons in metals.
• Evaluate A: Covalent compounds like glucose lack ions, so they do not conduct in molten or aqueous states.
• Evaluate B: Dilute acids ionize to produce free ions (e.g., H⁺ and SO₄²⁻ in H₂SO₄), enabling conduction.
• Evaluate C: Ionic compounds conduct via ion movement in solution or molten form, not electrons.
• Evaluate D: Metals conduct via delocalized electrons, not ion movement.

Why C is correct:

• Ionic solids like NaCl conduct electricity only when molten or dissolved, due to free-moving ions (Na⁺ and Cl⁻), per the definition of ionic conduction; electrons are fixed in ionic lattices.

Why the others are wrong:

• A is incorrect because glucose is a non-electrolyte with no ions, so it does not conduct.
• B is correct as stated, matching the ionization of acids producing mobile ions.
• D is incorrect because copper's conduction involves free electrons in a "sea" model, not positive ions.

Final answer: C