Answer
$m = 1.8\times 10^7~kg$
Work Step by Step
In part (a), we found that $2.7\times 10^{14}~J$ of energy was released.
We can find the required moles of TNT:
$\frac{2.7\times 10^{14}~J}{3.4\times 10^6~J} = 7.94\times 10^7~mol$
We can find the required mass of TNT:
$m = (7.94\times 10^7~mol)(0.227~kg/mol) = 1.8\times 10^7~kg$
