(a(i))[1]
State what the Avogadro constant $N_A$ means.
(a(ii))[2]
State what the mole means.
(b)[1]
A container has a volume of $1.8 \times 10^4\ \text{cm}^3$. The ideal gas inside the container has a pressure of $2.0 \times 10^7\ \text{Pa}$ at a temperature of $17^\circ\text{C}$. Show that the amount of gas in the cylinder is $150\ \text{mol}$.
(c(i))[2]
Gas molecules leak from the container in (b) at a constant rate of $1.5 \times 10^{19}\ \text{s}^{-1}$. The temperature stays at $17^\circ\text{C}$. In a time $t$, the amount of gas in the container is found to have dropped by $5.0\%$. Calculate the pressure of the gas after the time $t$.
(c(ii))[3]
Calculate the value of $t$.