Compound `(A)(C_(5)H_(10))` does not dissolve in cold conc. `H_(2)SO_(4)`.
What is `(A)`?

Options

A.
B.
C.
D.

Explanation

To determine the compound (A) with the molecular formula \( C_5H_{10} \) that does not dissolve in cold concentrated \( H_2SO_4 \), we can follow these steps:

### Step 1: Calculate the Degree of Unsaturation
The degree of unsaturation can be calculated using the formula:
\[ \text{Degree of Unsaturation} = \frac{2C + 2 - H}{2} \]
where \( C \) is the number of carbon atoms and \( H \) is the number of hydrogen atoms.

For \( C_5H_{10} \):
- \( C = 5 \)
- \( H = 10 \)

Plugging in the values:
\[ \text{Degree of Unsaturation} = \frac{2(5) + 2 - 10}{2} = \frac{10 + 2 - 10}{2} = \frac{2}{2} = 1 \]

### Step 2: Identify Possible Structures
With a degree of unsaturation of 1, the compound could be:
- A cycloalkane (which would have no double bonds)
- An alkene (which would have a double bond)

### Step 3: Analyze Solubility in Concentrated \( H_2SO_4 \)
Concentrated sulfuric acid typically reacts with alkenes (due to the presence of double bonds) and not with saturated hydrocarbons or cycloalkanes.

Since the problem states that compound (A) does not dissolve in cold concentrated \( H_2SO_4 \), we can conclude that (A) is likely a cycloalkane.

### Step 4: Determine the Structure of (A)
The only structure that fits the molecular formula \( C_5H_{10} \) and does not react with concentrated \( H_2SO_4 \) is cyclopentane.

### Conclusion
Thus, the compound (A) is **cyclopentane**.