The correct relationship between picometre and nanometre is

1 pm = ${10}^{-12} \mathrm{m}, 1 \mathrm{nm} = {10}^{-9}\mathrm{m}$

Conversion factor = $\frac{{10}^{-12}\mathrm{m}}{1 \mathrm{pm}} \mathrm{and} \frac{1 \mathrm{nm}}{{10}^{-9} \mathrm{m}}$

  $1 \mathrm{pm} = {10}^{12} \mathrm{m}\times \frac{1\mathrm{nm}}{{10}^{-9}\mathrm{m}}$

$\Rightarrow 1 \mathrm{pm} = {10}^{-3} \mathrm{nm}$

$\Rightarrow 1 \mathrm{nm} = 1000 \mathrm{pm}$