The physics behind the larger value of in-plane stiffness of CrS 2 is attributed to the highest value of cohesive energy per atom. In addition, the bond length between Cr and S is the lowest which holds creating the highest electrostatic pull that makes it much stiffer. Similarly, the larger values of Poisson's ratio of CrSe 2 and CrSSe indicate that these monolayers are more effective towards the uniaxial strain.