Which of the following is an incorrect statement?

FeO is non stoichiometric.

When interstitial compound is formed malleability and ductility are lost to a greater or lesser extent and the tenacity of the metal increases.

Cu⁺ disproportionate to Cu²⁺ and elemental copper in solution. 

Reduction using Lindlar's catalyst converts 2-butyne into trans-2-butene.