The partial pressure of a gas is the pressure that would be exerted by that gas alone if it occupied the same container on its own. In this case, we have 3 kmol of Gas A and 4 kmol of Gas B which are both held in separate containers of equal volume and when they are mixed together in a new container, again of equal volume the pressure reading is 10 bar. To calculate the partial pressure of A, we need to use Dalton’s law which states: “the total pressure within a container is equal to the sum of all individual gases present inside it”.

Therefore, we can solve for A’s partial pressure using this equation: P(A) = (n(A)/nT)*Ptotal where n(A) represents moles or number of molecules of gas A; nT represents moles or number molecules total (which equals 7 in this case); and Ptotal represents total pressure. Plugging these numbers into our equation gives us P(A) = (3/7)*10 bar=4.29 bar.