Answer:
The value is 

Step-by-step explanation:
From the question we are told that 
 The volume of the bottle is 

 The gauge pressure of the air is 

 
Generally the volume of air before the bottle is turned upside down is 
 

 

 

Generally the volume air when the bottle is turned upside-down is 
 

 

From the the mathematical relation of adiabatic process we have that 
 

Here r is a constant with a value r = 1.4 
 So 
 

 
