The intrinsic viscosity and molar mass were determined by light scattering. natural on $5$ fractions considered isomolecular of polystyrene in solution in butanone. The measurements are carried out at $25C.$

we give the values of $(\frac{C}{(I-I_0)}{)}_{,c}=0$ also the value of P$d$ of the slope at the origin of the angular dependence of $(\frac{C}{(I-I_0)}{)}_c=0$ which has the expression $($SEE TABLE ON PICTURE$)$

$1.$ Calculate the molar masses of the $5$ fractions.

$2.$ Calculate the radius of gyration of the molecules.

$3.$ Calculate the coefficients K and a of the Mark$-$Houvink equation for PS in butanone.

$3.$ Calculate the radii of gyration of molecules using the Flory$-$Fox relation.

$4.$ Compare with those obtained by light scattering. What is the law of variation of the radius of gyration with the molar mass?