A right $R$-module $P$ is $c$-separative provided that $Poplus Pstackrel{c}{cong} Poplus QLongrightarrow Pcong Q$ for any right $R$-module $Q$. We get, in this paper, two sufficient conditions under which a right module is $c$-separative. A ring $R$ is a hereditary ring provided that every ideal of $R$ is projective. As an application, we prove that every projective right $R$-module over a hereditary ring is $c$-separative.

Keywords: c-separativity, herediatry ring, projective module