Consider an aqueous colloidal dispersion of polymer coated silica particles.

i$)$ The neutron coherent scattering length density of the silica particle is

$3\mathrm{.}5$ x $1010$ cm$-2.$ Calculate the solvent composition $($to the nearest $5$ vol

$\%)$ that is required to contrast match the particles.

$[$rsld$($D$2$O$)=6\mathrm{.}4$ x $1010$ cm$-2,$ rsld$($H$2$O$)=-0\mathrm{.}56$ x $1010$ cm$-2]$