Step 1: Freundlich Adsorption Isotherm  
The Freundlich adsorption isotherm is given by:
\[
\frac{x}{m} = k P^{\frac{1}{n}}
\]
where:
- \( P \) is the gas pressure,
- \( k \) is a constant,
- \( n = 2 \).
 Step 2: Substituting Values  
\[
\frac{x}{m} = k \times 2^{\frac{1}{2}}
\]
\[
\frac{x}{m} = k \times \sqrt{2}
\]
Approximating \( \sqrt{2} \approx 1.414 \):
\[
\frac{x}{m} = 1.414k
\]
 Conclusion  
Thus, the correct answer is:
\[
1.414k
\]