At 300 mm hg, a gas has a volume of 380 l. what is its volume at standard pressure?

 V ^2 =  180 m L

Explanation:  For this question, we will issue that the change happens at constant temperature and that the gas behaves ideally.

We can use the ideal gas law:  

P V  =  n R T

Since the change is occurring at constant temperature and number of mole, we can modify the ideal gas law as follows:

P V  =  k  where,  k  =  n R T .

For position 1: we have  

P 1  and  V 1 .

For position 2: we will have  

P 2  and  V 2 .

Since  P V  =  k  we can write  P 1  V 1  =  P 2  V 2 .

Therefore,  V 2  =  P 1  V 1 / P 2

⇒  V 2  =  300 m m H g  × 300 m L /500 m m H g  = 180 m L