Which of the following products is formed when n-heptane is passed over `(Al_(2)O_(3)+Cr_(2)O_(3))` catalyst at 773K?

Options

A. Benzene
B. Toluene
C. Polyheptane
D. Cycloheptane

Explanation

To solve the question of which product is formed when n-heptane is passed over an `(Al_(2)O_(3)+Cr_(2)O_(3))` catalyst at 773K, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reaction Type**:
- When n-heptane (C7H16) is passed over a catalyst like `(Al_(2)O_(3)+Cr_(2)O_(3))`, it undergoes a process known as aromatization. This process involves the conversion of aliphatic hydrocarbons into aromatic hydrocarbons.

**Hint**: Look for reactions that convert straight-chain alkanes into aromatic compounds.

2. **Understand the Structure of n-Heptane**:
- n-Heptane is a straight-chain alkane with the formula C7H16. Its structure is CH3-CH2-CH2-CH2-CH2-CH2-CH3.

**Hint**: Visualize the molecular structure of n-heptane to understand how it can be transformed.

3. **Determine the Product of Aromatization**:
- During the aromatization of n-heptane, the molecule loses hydrogen atoms and rearranges to form an aromatic compound. The most common aromatic product from n-heptane is toluene (C7H8), which consists of a benzene ring (C6H6) with a methyl group (CH3) attached.

**Hint**: Recall that aromatic compounds are typically cyclic and have alternating double bonds.

4. **Write the Chemical Reaction**:
- The reaction can be summarized as follows:
\[ \text{C7H16 (n-heptane)} \xrightarrow{(Al_2O_3 + Cr_2O_3), 773K} \text{C7H8 (toluene)} + \text{H}_2 \]

**Hint**: Remember that during the conversion, hydrogen gas is often released.

5. **Select the Correct Product**:
- Based on the above analysis, the product formed when n-heptane is passed over `(Al_(2)O_(3)+Cr_(2)O_(3))` at 773K is toluene.

**Hint**: Compare the structure of the expected product (toluene) with other possible products to confirm its formation.

### Final Answer:
The product formed is **toluene (C7H8)**.