At STP , the density of` C H_(4) `vapour in g/L will be nearest to

Options

A. 6.87
B. 0.71
C. 3.84
D. 1.87

Answer

To find the density of CH₄ (methane) vapor at STP (Standard Temperature and Pressure), we can follow these steps:

### Step 1: Determine the molar mass of CH₄
- The molar mass of carbon (C) is approximately 12 g/mol.
- The molar mass of hydrogen (H) is approximately 1 g/mol.
- Since CH₄ has one carbon atom and four hydrogen atoms, we calculate the molar mass as follows:
\[ \text{Molar mass of CH₄} = 12 \, \text{g/mol (C)} + 4 \times 1 \, \text{g/mol (H)} = 12 + 4 = 16 \, \text{g/mol} \]

### Step 2: Use the volume of one mole of gas at STP
- At STP, one mole of any ideal gas occupies a volume of 22.4 liters.

### Step 3: Calculate the density
- Density (D) is defined as mass (m) divided by volume (V):
\[ D = \frac{m}{V} \]
- We know the mass of one mole of CH₄ is 16 g and the volume at STP is 22.4 L. Therefore:
\[ D = \frac{16 \, \text{g}}{22.4 \, \text{L}} \approx 0.7143 \, \text{g/L} \]

### Step 4: Round the result
- Rounding 0.7143 g/L gives us approximately 0.71 g/L.

### Final Answer
- The density of CH₄ vapor at STP is nearest to **0.71 g/L**.

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