Question

Two identical cylinders contain helium at 2.5 atm and argon at 1 atm respectively. If both the gases are filled in one of the cylinders, the pressure would be:

• A. 3.5 atm
• B. 1.50 atm
• C. 1.75 atm
• D. 1 atm

Hint:

When gases from equal volumes at same temperature are combined into one of them, pressures simply add.

Answer 1

The Correct Option is A

Concept: Using ideal gas law: \[ PV = nRT \]

Step 1: Initial moles.
For identical cylinders (same \(V, T\)): \[ n_1 = \frac{P_1 V}{RT}, \quad n_2 = \frac{P_2 V}{RT} \]

Step 2: Total moles.
\[ n_{\text{total}} = \frac{(P_1 + P_2)V}{RT} \]

Step 3: Final pressure.
Now gases are in one cylinder (volume \(V\)): \[ P = \frac{n_{\text{total}} RT}{V} = P_1 + P_2 \] \[ P = 2.5 + 1 = 3.5 \, \text{atm} \]