Omitted question:I think you mean Gas A and D each exert 120 mm Hg, if Gas D has a different value , just lug it into he equation as shown below and solve.
Answer:Gas C= 670mmHg
Step-by-step explanation:
According to Dalton law of partial pressure
The total pressure of a mixture of gases is the sum of the pressures of each gas and can be illustrated as
Pressure total=P1+P2+… +Pn.
Total Pressure = Gas A + Gas B + Gas C + Gas D + Gas...
Now we have
Total Pressure = 120 mm Hg + 50mm Hg + Gas C + 120 mm Hg
960mmHg = 120 mm Hg + 50mm Hg + Gas C + 120 mm Hg
960mmHg =290mmHg +Gas C
Gas C =960mmHg -290mmHg
Gas C= 670mmHg