Assuming constant pressure and temperature, how many moles of gas have been added to the initial 3 moles of gas when the volume increases from 2.0 to 4.0 liters?
1.5 moles
2 moles
3 moles
6 moles

Moles of gas added = 3 moles

Explanation:

Given:

Initial volume of gas, V1 = 2.0 L

Initial moles of gas, n1 = 3 moles

Final volume, V2 = 4.0 L

To determine:

The moles of gas added to bring the final volume to 4.0 L

Explanation:

Based on the ideal gas equation

where P = pressure, V = volume ; n = moles of gas

R = gas constant, T = temperature

At constant P and T, the above equation becomes:

V/n = constant

This is the Avogadro's law

Therefore:

The final number of moles of gas = 6

Thus, moles added = Final - Initial = n2 - n1 = 6-3 = 3 moles

a is the correct answer