Which characteristic that a scientific measuring tool should have?

An equilibrium mixture of pcl5(g), pcl3(g), and cl2(g) has partial pressures of 217.0 torr, 13.2 torr, and 13.2 torr, respectively. a quantity of cl2(g) is injected into the mixture, and the total pressure jumps to 263.0 torr (at the moment of mixing). the system then re-equilibrates. the appropriate chemical equation is pcl3(g)+cl2(g) < --> pcl5(g) calculate the new partial pressures after equilibrium is reestablished in torr