In this paper we first introduce quermassintegrals for free boundary hypersurfaces in the $(n+1)$-dimensional Euclidean unit ball. Then solve some related isoperimetric type problems convex hypersurfaces, which lead to new Alexandrov–Fenchel inequalities. particular, $n = 2$ obtain a Minkowski-type inequality and 3$ an optimal Willmore-type inequality. To prove these estimates, employ specifica...