A barometer kept is an elevator reads 76cm when the elevator is accelerating upwards. The most likely pressure inside the elevator (in cm of Hg) is

• 74
• 75
• 76
• 77

under normal conditions when the elevator is accelerating upwards the reading in the barometer will be less than 76cm (air pressure is same as external) but as acc. to question the pressure is 76 cm means that the air is applying more pressure to lift the liquid to a height of 76cm.so the air pressure in the lift is higher than the normal(76 cm).

the liqiud becomes heavier m*(g+a) when the lift accelerating upwards. so it requires more more pressure from the air onto the liquid to rise at the height of 76 cm.

Hence answer is 77