(a)[2]
Describe how molecules move in a gas, according to the kinetic theory of gases.
(b)[2]
Describe the observation seen when Brownian motion is viewed that supports your answer in (a).
(c(i))[3]
With $1.00\,\text{mol}$ of helium gas at a pressure of $1.05 \times 10^5\,\text{Pa}$ and a temperature of $27^{\circ}\text{C}$, the volume is $0.0240\,\text{m}^3$. The mass of $1.00\,\text{mol}$ of helium gas, treated as an ideal gas, is $4.00\,\text{g}$. Calculate the root-mean-square (r.m.s.) speed of an atom of helium gas for a temperature of $27^{\circ}\text{C}$.
(c(ii))[3]
Using your answer in (i), determine the r.m.s. speed of the atoms at $177^{\circ}\text{C}$.