How many σ and π bonds are present in a molecule of cumulene? (figure 1) enter the number of σ bonds followed by the number of π bonds separated by a comma.

nanotechnology is a powerful tool in biomaterials research as it creates numerous possibilities for the engineering of functional molecules. nano-bio refers to projected ability to incorporate biomimicry into various materials at nanoscale.  

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.