A sealed syringe contains a fixed mass of air. The plunger is pulled slowly outward, increasing the volume of the air inside while keeping its temperature constant. Which statement correctly describes the change in air pressure and the reason for this change?
The pressure decreases because the air molecules move more slowly.
The pressure decreases because the air molecules strike the inside walls of the syringe less frequently.
The pressure increases because the air molecules move more quickly.
The pressure increases because the air molecules strike the inside walls of the syringe more frequently.
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.