  Based on first-principles calculations, we resent a method to reveal the
elastic properties of recently synthesized monolayer hydrocarbon, graphane. The
in-plane stiffness and Poisson's ratio values are found to be smaller than
those of graphene, and its yielding strain decreases in the presence of various
vacancy defects and also at high ambient temperature. We also found that the
band gap can be strongly modified by applied strain in the elastic range.
