Answer
The percentage deviation is $~~0.84~\%$
Work Step by Step
We can find the percentage deviation for $^{31}P$:
$\frac{M_{app}-M}{M}~\times 100\%$
$= \frac{A~m_p-30.973 762~u}{30.973 762~u}~\times 100\%$
$= \frac{(31)(1.673\times 10^{-27}~kg)-(30.973 762)(1.660538782\times 10^{-27}~kg)}{(30.973 762)(1.660538782\times 10^{-27}~kg)}~\times 100\%$
$= 0.84~\%$
The percentage deviation is $~~0.84~\%$
