A gas has molecular formula `(CH)_n`. If vapour density of the gas is 39, what should be the formula of the compound ?

Options

A. `C_3H_3`
B. `C_4H_4`
C. `C_2H_2`
D. `C_6H_6`

Explanation

To solve the problem, we need to determine the molecular formula of the gas given its vapor density. Here’s a step-by-step solution:

### Step 1: Understand the molecular formula
The molecular formula of the gas is given as \( (CH)_n \). This means that the gas consists of \( n \) carbon (C) atoms and \( n \) hydrogen (H) atoms.

### Step 2: Calculate the molar mass of the gas
The molar mass of one carbon atom is 12 g/mol and that of one hydrogen atom is 1 g/mol. Therefore, the molar mass of \( (CH)_n \) can be calculated as:
\[
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