Equal lengths of magnesium ribbons are taken in test-tubes A and B. Hydrochloric acid (HCI) is added to test-tube A while acetic acid (CH3COOH) is added to test-tube B. In which test-tube will the fizzing occur more vigorously and why?

When acid reacts with magnesium metal, hydrogen gas is produced which causes fizzing. Hydrochloric acid is a much stronger acid than acetic acid thus having greater number of hydrogen ions in it. Hence, during the chemical reaction with magnesium metal, hydrochloric acid will produce more hydrogen gas and the fizzing will be more vigorous in test-tube A.