Final answer:
Iron or aluminum can be used to test for hydrogen in place of zinc, as they will react with acids to release hydrogen gas.
Step-by-step explanation:
The student's question is about which metal can be used in place of zinc to test for the presence of hydrogen. The correct answer is Iron (Fe). When iron reacts with acids such as hydrochloric or sulfuric acid, it displaces hydrogen, forming iron salts and releasing hydrogen gas. This is because iron is more reactive than hydrogen but less reactive than the active metals like sodium or potassium. Aluminum (Al) can also be used for the test of hydrogen as it too will react with acids to produce hydrogen gas. Conversely, metals like copper (Cu) and silver (Ag) are less reactive than hydrogen and will not easily oxidize to release hydrogen gas when exposed to acids.