For each of the following bonds, indicate the positive end with $\delta^{+}$ and the negative end with $\delta^{-} .$ Draw an arrow to show the dipole for each.
a. $\mathrm{P}-\mathrm{Cl}$
b. $\mathrm{Se}-\mathrm{F}$
c. $\mathrm{Br}-\mathrm{F}$
d. $\mathrm{N}-\mathrm{H}$
e. $\mathrm{B}-\mathrm{Cl}$