A faulty mercury barometer contains a small amount of trapped air in the space above the mercury column. The temperature of this trapped air is increased.
As a result, the height of the mercury column decreases.
Why does this happen?
The trapped air molecules collide less frequently with the mercury surface.
The trapped air molecules exert more pressure on the mercury surface.
The density of the mercury in the column increases.
The atmospheric pressure acting on the open reservoir decreases.
321 exam-style questions on CIE IGCSE Physics 2.1 Kinetic particle model of matter, covering 2.1.1 States of matter and changes of state, 2.1.2a Particle structure and motion in solids, liquids and gases, 2.1.2b Gas pressure and particle collisions, 2.1.2c Brownian motion, 2.1.3a The absolute scale of temperature, and 2.1.3b Pressure, volume and temperature of a gas. Each one has a worked solution and a mark scheme showing where the marks go.