In a laboratory, a student generates a gas by adding dilute hydrochloric acid to zinc granules. The gas is collected and tested. Which test correctly identifies the gas?
Show the answer and explanation
Correct answer
B. A burning splint produces a pop sound
Principle or equation
Zinc reacts with dilute HCl to produce hydrogen gas. Hydrogen is flammable and produces a characteristic 'pop' sound when a burning splint is introduced.
Why this answer is correct
Zn + 2HCl → ZnCl2 + H2. Hydrogen gas burns with a pop sound. Oxygen relights a glowing splint; CO2 turns limewater milky; ammonia turns red litmus blue.
Example
Adding magnesium to dilute sulfuric acid produces hydrogen, which also gives a pop test.
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