Problem 12

C₇H₉N
Rule 3, omit the N and one H, gives C₇H₈
7 - 8/2 + 1 = 4 degrees of unsaturation.
Look for an aromatic ring, plus another pi bond or aliphatic ring.

The two bands at 3433 and 3354 indicate a primary amine (-NH₂). The bands at 3000-2850 indicate C-H alkane stretches. The band at 3034 indicates aromatic C-H stretch; aromatics also show bands in the regions 1600-1585 and 1500-1400 (C-C in-ring stretch), and 900-675 (C-H out-of-plane). C-N stretch of aromatic amines would show up at 1335-1250 (there is a band in that region).

This is the structure. See if you can assign the peaks on your own.

You are not expected to tell the aromatic Hs apart from each other, but you are expected to know that the ring is not para-substituted.