The 10% of total volume of the barometer liquid (mercury) contains impurities having an average density 5 g cm^(-3). When this faulty barometer is used to measure the atmospheric pressure it reads 80 cm of the liquid column. Determine the correct atmospheric pressure.

The 10% of total volume of the barometer liquid (mercury) contains imp

1.	The 10% of total volume of the barometer liquid (mercury) contains impurities having an average density 5 g cm^(-3). When this faulty barometer is used to measure the atmospheric pressure it reads 80 cm of the liquid column. Determine the correct atmospheric pressure.
Answer» Solution :(i) Volume of impurity =0.1 V Volume of `H_("mercury")=0.9 V` Density of the liquid in BAROMETER `=("total mass")/("total volume")` i.e., `d_(1)=(d_(Hg)xx0.9V + d_("impurity")xx 0.1 V)/(V)` Now the pressure recorded by a standard barometer `P_(1)=h_(Hg) d_(y) g` Pressure recorded by faulty barometer `P_(2)=h_(2)xx dl xx g` Equate (1) and (2) and DETERMINE value at `h_(Hg)`. (II) 75 cm