Q1: The equation,  is for

ANS:A - steady state equimolar counter diffusion

Steady-state equimolar counter diffusion refers to a scenario in which two different substances or species are simultaneously diffusing through a medium, and they are doing so at equal rates. Here's an explanation of each aspect:

1. Steady State: In a steady state, the concentrations of the diffusing substances do not change over time. This means that the rate at which each substance is entering the system is balanced by the rate at which it is leaving the system. In other words, there is a constant flow of each substance through the medium, leading to a stable concentration profile.
2. Equimolar: "Equimolar" means that the two substances have the same molar concentrations. In the context of counter diffusion, it implies that the molar flow rates of the two substances into the medium are equal. This condition ensures that the concentrations of the two substances remain constant throughout the medium as they diffuse.
3. Counter Diffusion: "Counter diffusion" refers to the movement of substances in opposite directions through a medium. In this case, the two substances are diffusing in opposite directions with respect to each other. For example, substance A may be diffusing from left to right, while substance B is diffusing from right to left.

Overall, steady-state equimolar counter diffusion occurs when two substances of equal concentration are diffusing through a medium in opposite directions, and their rates of diffusion are balanced such that their concentrations remain constant over time. This phenomenon has applications in various fields, including chemical engineering, where it can be utilized for processes such as membrane separations and mass transfer operations.