Answer:
18.94 mL.
Step-by-step explanation:
- We can use the general law of ideal gas: PV = nRT. 
where, P is the pressure of the gas in atm. 
 V is the volume of the gas in L. 
 n is the no. of moles of the gas in mol. 
 R is the general gas constant, 
 T is the temperature of the gas in K. 
 
- If n and T are constant, and have two different values of V and P: 
 P₁V₁ = P₂V₂ 
 
P₁ = 9.4 mm Hg, V₁ = 1531.0 mL. 
P₂ = 760.0 mm Hg, V₂ = ??? mL. 
 
∴ V₂ = P₁V₁/P₂ = (9.4 mm Hg)(1531.0 mL)/(760.0 mm Hg) = 18.94 mL.