$25.$ Fluidized beds are suitable for a wide range of applications, including chemical $\_\_\_$ and

physical $\_\_\_$ processes.

$26.$ The operation of packed beds is influenced by the particle $\_\_$ and the velocity of the $\_\_$ phase.

$27.$ Fluidized beds operate effectively when particles are suspended by an upward$-$flowing $\_,$ reaching a state of $\_$ fluidization.

$28.$ The pressure drop in packed beds is significantly influenced by the fluid flow rates and the properties of the packed $\_\_\_.$