Van Der Waals Equation

Step 1: Concept
The van der Waals' equation is .
Step 2: Analysis
Constant 'a' represents intermolecular forces, while 'b' is the volume correction.
Step 3: Conclusion
Constant 'b' arises due to the finite size of the molecules, measuring the excluded volume.
Final Answer: (C)

Step 1: Concept
The van der Waals' equation is .
Step 2: Analysis
Constant 'a' represents intermolecular forces, while 'b' is the volume correction.
Step 3: Conclusion
Constant 'b' arises due to the finite size of the molecules, measuring the excluded volume.
Final Answer: (C)

Step 1: Determine Bond Orders
Using Molecular Orbital Theory, the bond orders are: , , , and .
Step 2: Comparison
The values show a clear increasing sequence from 1 to 2.5.
Step 3: Arrangement
The correct increasing order is .
Final Answer: (a)

Step 1: Convergence
A converging lens focuses parallel rays at its focal point.
Step 2: Intensity Change
As you move toward the focal point, the light rays concentrate, so intensity increases.
Step 3: Divergence
After passing the focal point, the rays begin to diverge, causing the intensity to decrease.
Final Answer: (d)

Concept: Van der Waals equation:

Step 1: Convert temperature to Kelvin:


Step 2: Substitute given values:


Step 3: Solve for pressure:
Conclusion:
Pressure = 0.807 atm

Step 1: Understanding the Concept:
Real gases behave ideally when intermolecular forces are negligible.

Step 2: Detailed Explanation:
At extremely low pressure, volume is large, so molecular volume and intermolecular attractions become negligible. The van der Waals equation reduces to .

Step 3: Final Answer:
Extremely lower pressure.

Step 1: Understanding the Concept:
Van der Waals' equation corrects the ideal gas law for the finite size of gas molecules and intermolecular attractions.

Step 2: Detailed Explanation:
The van der Waals' equation for 1 mole of a real gas is: • The term 'b' is the volume correction. It accounts for the volume occupied by the gas molecules themselves. It is approximately four times the actual volume of the molecules. • 'a' is the pressure correction term, which accounts for intermolecular attractions.

Step 3: Final Answer:
Constant 'b' is a measure of the volume occupied by the molecules, which corresponds to option (A).