Abhipsatripathy last edited by
Given details give 5 cm of Hg is equal to 10 cm of air.
Now,length of extra column is Same in beaker. So,the mercury must rise upto (70+10) cm,which is 80 cm.
Given barometer reading is 75 cm of Hg now,which gives air length to be 5 cm.
This makes pressure of intial air double(P1V1=P2V2),i.e,10 cm of Hg.
Now,total pressure is sum of faulty pressure and shown pressure,which is (75+10) cm of Hg.
And:-850 mm of Hg.