Answer: The oxygen gas has a pressure of 4 atm if my volume decreases to 1 L.
Step-by-step explanation:
Given: 
 = 2 L,
 = 2 L, 
 = 2 atm
 = 2 atm
 = 1 L,
 = 1 L, 
 = ?
 = ?
Formula used to calculate the new pressure is as follows.

Substitute the values into above formula as follows.

Thus, we can conclude that the oxygen gas has a pressure of 4 atm if my volume decreases to 1 L.