Which of the following reactions represent valid methods for the preparation of dihydrogen gas? — Hydrogen Chemistry Question

💡 Solution & Explanation

Amphoteric metals like $Zn$ and $Al$ react with boiling alkali ($NaOH$) to liberate hydrogen gas. The reaction of methane with steam over a $Ni$ catalyst at $1270\text{ K}$ also produces syngas ($CO + H_2$). Copper ($Cu$) is below hydrogen in the reactivity series and does not displace $H_2$ from dilute acids.