JEE Advanced 2020 Full Test 2 Paper 1

A barometer has become faulty because some air has leaked into the space above the mercury column. The height of the mercury column is 70cm and the length of the space above the mercury is 10cm. The barometer tube is then pushed further down into the mercury through. The length of space above mercury reduces to 6cm and the height of the mercury column is found to decrease to 67cm. This information shows that the true atmospheric pressure must be: