Match the following
`{:(" Column I"," Column II"),("(A) "FeSO_(4)overset(Delta)rarr,"(p) A gas which gives green colour with acidified "K_(2)Cr_(2)O_(7)),("(B) "NaNO_(2)overset(dil HCl)rarrA"" overset(air)rarrB" (gas)","(q) A gas which form oleum with "H_(2)SO_(4)),("(C) "Na_(2)SO_(3)overset(dil(HCl))rarrP" (gas)","(r) A gas which is mixed anhydride of "HNO_(2) and NHO_(3)),("(D) "NaCl overset(conc. H_(2)SO_(4))rarrP" (gas)","(s) A gas which is also given by "AlCl_(3)" in moist air"),(,"(t) Green colour"):}`

Answer

To solve the matching question between Column I and Column II, we need to analyze the reactions given in Column I and identify the corresponding gases produced in Column II.

### Step-by-Step Solution:

1. **Identify the reaction for (A) FeSO₄ on heating:**
- When FeSO₄ (ferrous sulfate) is heated, it decomposes to form Fe₂O₃ (ferric oxide) and SO₂ (sulfur dioxide) and SO₃ (sulfur trioxide).
- The relevant gas here is SO₃, which can react with H₂SO₄ to form oleum (H₂S₂O₇).
- **Match (A) with (Q):** A gas which forms oleum with H₂SO₄.

2. **Identify the reaction for (B) NaNO₂ in dilute HCl:**
- When NaNO₂ (sodium nitrite) reacts with dilute HCl, it forms NaCl and HNO₂ (nitrous acid).
- HNO₂ decomposes in air to form nitrogen dioxide (NO₂), which is a mixed anhydride of HNO₂ and HNO₃ (nitric acid).
- **Match (B) with (R):** A gas which is a mixed anhydride of HNO₂ and HNO₃.

3. **Identify the reaction for (C) Na₂SO₃ in dilute HCl:**
- Na₂SO₃ (sodium sulfite) reacts with dilute HCl to produce NaCl, SO₂, and water.
- SO₂ is the gas produced, which gives a green color when passed through acidified K₂Cr₂O₇ (potassium dichromate).
- **Match (C) with (P):** A gas which gives green color with acidified K₂Cr₂O₇.

4. **Identify the reaction for (D) NaCl with concentrated H₂SO₄:**
- NaCl reacts with concentrated H₂SO₄ to produce Na₂SO₄ and HCl gas.
- HCl is also produced when AlCl₃ reacts with moisture in the air.
- **Match (D) with (S):** A gas which is also given by AlCl₃ in moist air.

### Final Matches:
- (A) → (Q)
- (B) → (R)
- (C) → (P)
- (D) → (S)