# Process Calculations GATE-2020

**Q 1: **A tank initially contains a gas mixture with 21 mol % oxygen and 79 mol % nitrogen. Pure nitrogen enters the tank, and a gas mixture of nitrogen and oxygen exits the tank. The molar flow rate of both the inlet and exit streams is 8 mol/s. In addition, use the following data and assumptions

- Assume the tank contents to be well mixed
- Assume ideal gas behavior
- The temperature and pressure inside the tank are held constant
- The molar density of the gas mixture in the tank is constant at 40 mol.m
^{-3}

If the volume of the tank is 20 m^{3}, then the time (in seconds) required for oxygen content in the tank to decrease to 1 mol % is

**Q 2: **A feed stream containing pure species L flows into a reactor, where L is partly converted to M as shown in the figure.

The mass flow rate of the recycle stream is 20 % of that of the product steam. The overall conversion of L (based on mass units) in the process is 30 %. Assuming steady-state operation, the one-pass conversion of L (based on mass units) through the reactor is