Experiment: Dilute nitric acid was added to powdered iron in a beaker.Observation: A brown gas was released, and the solution turned light green.Question: What does this indicate?
Correct answer: B. Iron reacts with nitric acid to form iron nitrate and NO₂.
- A. Iron gets coated with brown rust.
- B. Iron reacts with nitric acid to form iron nitrate and NO₂.
- C. Gas is hydrogen released during rusting.
- D. Green color is due to iron oxidation into Fe³⁺.
Explanation
The brown gas observed is nitrogen dioxide (NO₂) formed when iron reacts with nitric acid. The light green solution indicates the formation of iron nitrate. The other options are incorrect because they do not align with the specific observations mentioned in the experiment.
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About Scientific Reasoning
Scientific reasoning evaluates hypotheses through observations, variables, controls, measurements and experimental results. Questions involve identifying independent and dependent variables, recognising a fair test, interpreting tables or graphs, distinguishing evidence from opinion, and deciding whether data supports, rejects or leaves a hypothesis unresolved.
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