Answer
$8.9 \times 10^{-5} s^{-1}$
Work Step by Step
Association rate = $8.9 \times 10^{3} M^{-1} s^{-1}$
Dissociation constant = 10nM = $10 \times 10^{-9}M$
Dissociation rate=?
Dissociation constant = Dissociation rate $\div $ Association rate
Dissociation rate = Dissociation constant $\times$ Association rate
Dissociation rate = $10 \times 10^{-9}M$ $\times$ $8.9 \times 10^{3} M^{-1}s^{-1}$
= $8.9 \times 10^{-5} s^{-1}$