The chief source of iodine in which it is present as sodium iodate is

Options

A. Sea water
B. Caliche
C. Carnallite
D. Iodine never exists as sodium iodate

Explanation

To solve the question regarding the chief source of iodine in which it is present as sodium iodate, we can follow these steps:

### Step-by-Step Solution

1. **Identify the Compound**: The question mentions sodium iodate (NaIO3). We need to find out where this compound is primarily sourced from.

2. **Understand Sodium Iodate**: Sodium iodate is a compound that contains iodine. It is important to note that iodine is a halogen and is found in various natural sources.

3. **Research Sources of Iodine**: The primary sources of iodine include seaweed, certain fish, and some minerals. However, in the context of sodium iodate, we need to look for a specific mineral or compound.

4. **Identify the Correct Source**: The transcript mentions "chili salt peter," which is known as sodium nitrate (NaNO3). It is important to note that sodium iodate can be found as an impurity in sodium nitrate.

5. **Concentration of Sodium Iodate**: The transcript states that sodium iodate is present as an impurity at a concentration of about 0.02% in chili salt peter.

6. **Conclusion**: Based on the information gathered, the chief source of iodine in which it is present as sodium iodate is chili salt peter (sodium nitrate, NaNO3).

### Final Answer
The chief source of iodine in which it is present as sodium iodate is chili salt peter (sodium nitrate, NaNO3).