The correct option is A 1.8 bar
Partial pressure of hydrogen gas
V1=0.5 L V2=1.0 L
P1=0.8 bar P2=?
Applying Boyle's law (constant T and n)
P1V1=P2V2 or P2=P1V1V2
∴P2=(0.8 bar)×(0.5 L)(1.0 L)=0.40 bar
Partial pressure of oxygen gas,
V1=2.0 L,V1=1.0 L
P1=0.7 bar P2=?
or P2=P1V1V2=(0.7 bar)×(2.0 L)(1.0 L)=1.40 bar.
Pressure of the gas mixture,
Pminx=PH2+PO2=0.40+1.40=1.80 bar.