ANS:A - 1

For a binary mixture distillation process with fixed pressure, the number of independent variables is 3. Explanation:

1. In a binary mixture distillation process, the degree of freedom (DOF) is given by the formula: 𝐷𝑂𝐹=𝐶−𝑃+2DOF=C−P+2 Where:
   • 𝐶C is the number of components (2 for a binary mixture).
   • 𝑃P is the number of phases (2 for liquid and vapor phases).
   • The constant +2+2 accounts for the temperature and pressure variables.
2. Substituting 𝐶=2C=2 and 𝑃=2P=2 into the formula, we get: 𝐷𝑂𝐹=2−2+2=2DOF=2−2+2=2
3. However, if the pressure is fixed in the distillation process, it becomes a constraint, reducing the degrees of freedom by 1. This means the number of independent variables decreases by 1.
4. The independent variables in the process are typically temperature, composition, and flow rates. With pressure fixed, temperature and composition are the only independent variables remaining.
5. Therefore, with fixed pressure, the number of independent variables becomes 2−1=12−1=1.