A \(2000-\mathrm{m}^{3}\) vessel containing liquid methanol must be prepared for entry. After draining, it must first be purged with nitrogen ( \(98 \%\) nitrogen and \(2 \%\) oxygen from a membrane unit) and then purged with air to reach a fuel composition of \(0.1 \%\) of the TLV-TWA. Use sweep through purging, assuming a pressure of 1 \(\mathrm{atm}\), a temperature of \(25^{\circ} \mathrm{C}\), and purging rates (for nitrogen and air) of \(10 \mathrm{~m}^{3} / \mathrm{min}\).

a. Determine the composition of the vapor in the tank after draining.

b. Determine the target fuel composition for purging with nitrogen (with \(2 \%\) oxygen).

c. Determine the amount of nitrogen (in \(\mathrm{kg}\) ) required.

d. Determine the quantity of sweep through air required.