X' compound `(C_(4)H_(8)O)` decolorises bromine water react with `I_(2)` & NaOH it give yellow ppt identify 'X'

Options

A. `CH_(3)-overset(O)overset(||)(C)-CH_(2)-CH_(3)`
B. `CH_(3)-underset(OH)underset(|)(CH)-CH=CH_(2)`
C. `CH_(3)-overset(CH_(3))overset(|)underset(OH)underset(|)(C)-CH_(3)`
D. `CH_(3) -HC=CH-underset(OH)underset(|)(CH_(2))`

Explanation

To identify the compound X with the molecular formula \( C_4H_8O \), we will follow these steps:

### Step 1: Analyze the Molecular Formula
The molecular formula \( C_4H_8O \) indicates that the compound has 4 carbon atoms, 8 hydrogen atoms, and 1 oxygen atom. This suggests that the compound could be unsaturated (having double bonds) since the hydrogen count is lower than that of a saturated compound.

**Hint:** Look for the degree of unsaturation using the formula \( \text{Degree of Unsaturation} = \frac{(2C + 2 - H)}{2} \).

### Step 2: Test for Unsaturation
The compound is said to decolorize bromine water, which is a test for unsaturation. This indicates that X must contain at least one double bond between carbon atoms (C=C).

**Hint:** Remember that alkenes and alkynes can decolorize bromine water due to their double or triple bonds.

### Step 3: Identify Possible Structures
We will consider possible structures for \( C_4H_8O \) that can decolorize bromine water. The following structures could be considered:
1. Butene (C4H8)
2. 2-butanol (C4H10O)
3. 3-buten-2-ol (C4H8O)
4. 2-butanone (C4H8O)

Among these, we need to check which of these compounds can decolorize bromine water.

**Hint:** Focus on structures that contain C=C bonds.

### Step 4: React with Iodine and Sodium Hydroxide
The question states that X reacts with iodine (I2) and sodium hydroxide (NaOH) to give a yellow precipitate. This reaction is characteristic of the iodoform test, which indicates the presence of a methyl ketone or a secondary alcohol with a methyl group adjacent to the hydroxyl group.

**Hint:** Look for compounds that can produce a yellow precipitate when treated with iodine and NaOH.

### Step 5: Determine the Structure of X
Among the identified structures, we need to check which one can give a yellow precipitate:
- **2-butanol** (secondary alcohol with a methyl group adjacent) will give a yellow precipitate.
- **2-butenone** (methyl ketone) will also give a yellow precipitate.

However, since the compound must also decolorize bromine water, we can conclude that **2-butanol** is the correct structure because it is a secondary alcohol that meets both criteria.

**Hint:** Verify the structure by checking if it meets both the unsaturation and iodoform test requirements.

### Conclusion
Thus, the compound X is **2-butanol** (or 2-butanone, depending on the context, but primarily 2-butanol fits both tests).

**Final Answer:** The compound X is **2-butanol**.