(a)
For the correct answer (any three):
Random arrangement, widely spaced, random motion, high speed, or colliding with each other/walls.
In a gas, particles possess a high amount of kinetic energy, allowing them to overcome intermolecular forces almost completely. Consequently, the particles are widely separated and lack any fixed or regular arrangement. They move freely and randomly at high speeds, constantly colliding with one another and the walls of their container.
(b)(i)
For the correct answer:
$5.4\text{ J}$
Mechanical work is done when a force causes an object to move over a distance. The work done is calculated using the equation $W = F \times d$, where $F$ is the applied force and $d$ is the distance moved in the direction of the force. Substituting the given values, the work done is $W = 30\text{ N} \times 0.18\text{ m} = 5.4\text{ J}$.
(b)(ii)
For the correct answer:
The pressure increases because the collisions of the gas particles with the walls are more frequent / occur more often.
When the piston is pushed inwards, the volume of the container decreases, compressing the same mass of gas into a smaller space. Since the temperature is constant, the average kinetic energy and speed of the gas particles remain unchanged. However, because the space is smaller, the particles have a shorter distance to travel between the walls, leading to more frequent collisions with the walls. This higher rate of collision exerts a greater average force per unit area, thereby increasing the gas pressure ($p = \frac{F}{A}$).
