(a(i))[1]
State the meaning of the symbol $N$.
(a(ii))[1]
State the meaning of the symbol $\langle c^2 \rangle$.
(b(i).1)[3]
A gas cylinder of volume $2.1 \times 10^4\,\text{cm}^3$ contains helium-4 gas at pressure $6.1 \times 10^5\,\text{Pa}$ and temperature $12^\circ\text{C}$. Helium-4 may be assumed to be an ideal gas. Determine, for the helium gas, the amount, in mol.
(b(i).2)[2]
Determine, for the helium gas, the number of atoms.
(b(ii))[3]
Calculate the root-mean-square (r.m.s.) speed for the helium atoms.