A closed vessel with rigid walls contains 1 mole of `._(92)^(238)U` and 1 mole of air at `298K`. Considering complete decay of `._(92)^(238)U` to `._(82)^(206)Pb`the ratio of the final pressure to the initial pressure of the system at `298K` is

Explanation

`{:(238),(92):}U rarr {:(206),(82):}Pb + 8 alpha +6 beta`
`alpha` on getting neutralized forms He gas. So 1 mole `{:(238),(92):}U` produces 8 moles He Initial number of mole of gases = 1 mole Final number of mole of gases = 1 + 8 = 9 moles Ratio of final pressure to initial `=(9)/(1)=9 (P prop n)`