Assuming $^{1}J_{PH} > J_{PB}$ the expected $^{31}\mathrm{P}$ NMR spectrum of $\mathrm{H_3P.^{11}BCl_3}$ [for $^{11}\mathrm{B}$, $\mathrm{I}=3/2$] is
(a)
(b)
(c)
(d)
Answer
Answer: C ✓ checked by 4AB · confidence medium
Explanation
³¹P couples to three ¹H (large ¹J) to give a 1:3:3:1 quartet. Each line is split again by ¹¹B (I = 3/2) into four equal lines: a quartet of 1:1:1:1 quartets (c).