The curve that best describes the adsorption of a gas $\left(\mathrm{x}\right)\mathrm{g}$ on $1.0 \mathrm{g}$ of a solid substrate as a function of pressure $\left(\mathrm{p}\right)$ at a fixed temperature

 is

• A

  $1$
• Correct answer
  B

  $2$
• C

  $3$
• D

  $4$

Hence, the correct answer is option: 'B'.