Reaction of substances with dilute HCl

Steps:

• Identify contents of each test tube (e.g., metals, carbonates, bases).
• Recall HCl as a strong acid reacts with bases/neutralizers to form salts and water, with metals to produce hydrogen gas.
• Predict observations: effervescence for carbonates, no reaction for inert substances.
• Match predicted effect to option describing common outcomes like gas evolution or color change.

Why B is correct:

• B describes gas evolution from acid-base neutralization, per the reaction: acid + carbonate → salt + water + CO₂.

Why the others are wrong:

• A ignores reactivity differences, assuming uniform no reaction.
• C overstates precipitation without evidence of insoluble products.
• D misapplies to non-acidic contexts like oxidation.

Not enough information on specific test tube contents for precise effects.

Final answer: B