Identify the substance R based on the information given below:
The pale green solid R turns reddish brown on heating. Its aqueous solution gives a white precipitate with barium chloride solution. The precipitate is insoluble in mineral acids.

Explanation

To identify the substance R based on the given information, we can follow these steps:

### Step 1: Analyze the Color Change
The problem states that the substance R is a pale green solid that turns reddish brown upon heating. This indicates that R is likely a compound that undergoes a change in oxidation state or a decomposition reaction when heated.

**Hint:** Look for compounds that are known to change color when heated, particularly those that are pale green and can form reddish-brown products.

### Step 2: Identify the Possible Compound
...