Answer
Please see the work below.
Work Step by Step
We know that
$\frac{-1267KJ}{4mol\space NH_3}\times \frac{1mol\space NH_3}{17.03g}=-18.60\frac{KJ}{g}$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.