Let the first container contain x mol of gas then PV = xRT i.e. V=xRT as P=1 atm
Then the second container will contain 2x moles, the third will contain 3x moles and so on, the tenth container would contain 10x moles.
When all are connected by the tubes, the total volume would be 10V
The total number of moles of the gas=x+2x+3x+…10x= x ×(n)(n+1)2, where n = 11
⟹ 55x mol
Let the final pressure be Pt, then
Pt×10V=55xRT⇒Pt×10V=55V
⇒Pt=5.5 atm