Question

Short answer

a.

b.

Step-by-step solution

Amines  

Amines contain nitrogen; therefore, they are called nitrogen-containing compounds. They also contain lone pairs of electrons. Therefore, amines are called Lewis bases.

IR of amines 

The IR range of amines is 3300 to 3400$\mathrm{c}{\mathrm{m}}^{-1}$. The nitrogen protons give a broad signal.

Explanation

The degree of unsaturation is 4.

IR absorption at 3365$\mathrm{c}{\mathrm{m}}^{-1}$: N–H, 3284$\mathrm{c}{\mathrm{m}}^{-1}$: N–H, 3026$\mathrm{c}{\mathrm{m}}^{-1}$,${\mathrm{C}}_{\mathrm{s}{\mathrm{p}}^2}-\mathrm{H}$2932$\mathrm{c}{\mathrm{m}}^{-1}$,${\mathrm{C}}_{\mathrm{s}{\mathrm{p}}^3}-\mathrm{H}$1603$\mathrm{c}{\mathrm{m}}^{-1}$: due to benzene 1497$\mathrm{c}{\mathrm{m}}^{-1}$: due to benzene: CO

NMR data:

Multiplet at 7.2–7.4 ppm, 5 H on a benzene ring.

${\mathrm{H}}_{\mathrm{a}}$: triplet at 2.9 ppm, 2 H, split by 2 H's

${\mathrm{H}}_{\mathrm{b}}$: triplet at 2.8 ppm, 2 H, split by 2 H's

${\mathrm{H}}_{\mathrm{c}}$: singlet at 1.1 ppm, 2 H, no splitting (on $\mathrm{N}{\mathrm{H}}_2$)

The degree of unsaturation is 4.

IR absorptions at 3367$\mathrm{c}{\mathrm{m}}^{-1}$: N–H 3286$\mathrm{c}{\mathrm{m}}^{-1}$: N–H 3027$\mathrm{c}{\mathrm{m}}^{-1}$:${\mathrm{C}}_{\mathrm{s}{\mathrm{p}}^2}-\mathrm{H}$2962${\mathrm{C}}_{\mathrm{s}{\mathrm{p}}^3}-\mathrm{H}$: 1604$\mathrm{c}{\mathrm{m}}^{-1}$: due to benzene 1492$\mathrm{c}{\mathrm{m}}^{-1}$: due to benzene

NMR data: multiplet at 7.2–7.4 ppm, 5 H on a benzene ring

${\mathrm{H}}_{\mathrm{a}}$: quartet at 4.1 ppm, 1 H, split by 3H's ${\mathrm{H}}_{\mathrm{b}}$: singlet at 1.45 ppm, 2 H, no splitting $\left(\mathrm{N}{\mathrm{H}}_2\right)$ ${\mathrm{H}}_{\mathrm{c}}$: doublet at 1.4 ppm, 3 H, split by 1 H