A uniform capillary tube, sealed on one end, contains a column of air trapped by a thread of mercury $$85$$ mm long.

When the tube was held horizontally, the length of the air column was $$50$$ mm, but when it was held vertically with the sealed end pointing down, the length of the column became $$45$$ mm.

Find the surrounding atmospheric pressure in Pascals.

Take $$g$$ = $$10$$ m/s^2 and the density of mercury to be $$14000$$ kg/m^3.

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