Answer and explanation

Correct answer: B. Oxygen and moisture

  1. Step 1: Rusting needs both oxygen and water; without either one iron does not rust. Answer: Oxygen and moisture. Why not the others: Nitrogen and carbon dioxide, Hydrogen and light and Argon and dry air don't fit.

Practise more Chemistry: matter, reactions and carbon compounds.

Free questions with an explanation for every one, and full timed SEE (Secondary Education Examination, Nepal) mock tests.