Which of the following gases turns acidified potassium dichromate () paper from orange to green? — Qualitative and Quantitative Analysis Chemistry Question

💡 Solution & Explanation

Sulphur dioxide ($SO_2$) is a reducing agent that reduces the orange dichromate ion ($Cr_6^+$) to the green chromium ion ($Cr^{3+}$). $CO_2$ does not give this test.