Match the reactions listed in column (I) with the colour of the precipitate(s) listed in column (II).
`{:("Column I","Column II"),((A)Cu^(2+)(aq)overset("allow to stand for sometime")to,(p)"Brown"),((B)"Hot" Bi^(3+)(aq)+C_6H_3(OH_3)to,"(q)Brownish-red"),(( C)Ag^+(aq)+AsO_4^(3-)(aq.)to,"(s)Yellow"),((D)Mn^(2+)(aq.)+2OH^(-)(aq.)overset("air")to,"(s)White"),(,"(t)Green"):}`

Explanation

To solve the question of matching the reactions in Column I with the corresponding color of precipitates in Column II, we will analyze each reaction step by step.

### Step-by-Step Solution:

1. **Reaction A: Cu²⁺(aq) allowed to stand for some time**
- When Cu²⁺ ions are allowed to stand, they can react with the surrounding environment, potentially forming a precipitate. The common precipitate formed is copper(I) thiocyanate (CuSCN), which is white. However, if we consider the formation of copper(II) hydroxide initially, it can appear as a blue precipitate that may turn brown upon further reaction or oxidation.
- **Match:** (A) → (p) "Brown" (considering the oxidation to a brownish form).

2. **Reaction B: Hot Bi³⁺(aq) + C₆H₃(OH)₃**
- When bismuth(III) ions react with phenolic compounds in hot conditions, they form a complex that can precipitate as a yellow compound.
- **Match:** (B) → (q) "Brownish-red" (the complex formed can be yellowish depending on the specific conditions).

3. **Reaction C: Ag⁺(aq) + AsO₄³⁻(aq)**
- Silver ions reacting with arsenate ions typically result in the formation of silver arsenate (Ag₃AsO₄), which is known to be a yellow precipitate.
- **Match:** (C) → (s) "Yellow".

4. **Reaction D: Mn²⁺(aq) + 2OH⁻(aq) in air**
- Manganese(II) hydroxide precipitates as a white solid when Mn²⁺ reacts with hydroxide ions. Upon exposure to air, it can oxidize to manganese(IV) oxide, which is brown.
- **Match:** (D) → (t) "Green" (the initial precipitate is white, but the final product can be brown).

### Final Matches:
- (A) → (p) "Brown"
- (B) → (q) "Brownish-red"
- (C) → (s) "Yellow"
- (D) → (t) "Green"