When nickel reacts with dilute sulphuric acid, it produces hydrogen gas. The reaction can be represented by the following equation:

Ni + H2SO4 → NiSO4 + H2

In this reaction, nickel metal (Ni) reacts with sulfuric acid (H2SO4) to produce nickel sulfate (NiSO4) and hydrogen gas (H2). The hydrogen gas is released as bubbles and can be collected over water.