Question

Pendular state in drying of wet solids generally refers to:

• A. Constant rate
• B. First falling rate
• C. Second falling rate
• D. Equilibrium

Hint:

Pendular state appears late in drying when only bound moisture remains — it’s part of the second falling rate period.

Answer 1

The Correct Option is C

During the drying of wet solids, the process typically goes through three phases: constant rate period, first falling rate period, and second falling rate period.
- The pendular state refers to the condition when most of the free moisture has already evaporated, and only thin films of water remain around the solid particles.
- This occurs during the second falling rate period, where moisture movement is controlled primarily by diffusion through the solid structure.
In contrast:
- Constant rate period is associated with surface moisture evaporation.
- First falling rate marks the beginning of a decline in drying rate after surface moisture depletes.
- Equilibrium represents the end state where no further moisture loss occurs.
Hence, the pendular state is best associated with the second falling rate period of drying.