The principal products obtained on heating iodine with cold and concentrated caustic soda solution:

Options

A. `NaIO+NaI`
B. `NaIO+NaIO_(3)`
C. `NaIO_(3)+NaI`
D. `NaIO_(4)+NaI`

Explanation

To determine the principal products obtained when iodine (I2) is heated with cold and concentrated caustic soda (sodium hydroxide, NaOH), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants:**
- The reactants in this reaction are iodine (I2) and sodium hydroxide (NaOH) in a cold and concentrated solution.

2. **Write the Reaction:**
- The reaction can be represented as:
\[ I_2 + NaOH \rightarrow \text{Products} \]

3. **Determine the Products:**
- When iodine reacts with cold and concentrated sodium hydroxide, the principal products formed are sodium iodate (NaIO3) and sodium iodide (NaI), along with water (H2O).

4. **Write the Balanced Chemical Equation:**
- The balanced equation for the reaction is:
\[ 3 I_2 + 6 NaOH \rightarrow 5 NaI + NaIO_3 + 3 H_2O \]
- Here, we have:
- 3 molecules of iodine (I2)
- 6 molecules of sodium hydroxide (NaOH)
- Producing 5 molecules of sodium iodide (NaI), 1 molecule of sodium iodate (NaIO3), and 3 molecules of water (H2O).

5. **Identify the Principal Products:**
- From the balanced equation, the principal products are sodium iodate (NaIO3) and sodium iodide (NaI).

### Final Answer:
The principal products obtained on heating iodine with cold and concentrated caustic soda solution are sodium iodate (NaIO3) and sodium iodide (NaI).