An excited state of this element named for Hoyle is important in stellar nucleosynthesis. One moleculecreated from this element isomerises to create Stone-Wales defects, and that form is purified using amixture of DBU and trimethylbenzene. One form of this element is produced when cosmic rays bombardnitrogen. Chemical shifts between 0 and 200 ppm are observed in a type of NMR that observes a form ofthis element. Kroto, Smalley, and Curl found an unusual form of this element which forms a ball-likestructure. A sample of one type of this element is used in the precise definition of Avogadro's number,while another form of this element has a half-life of 5700 years. For 
An excited state of this element named for Hoyle is important in stellar nucleosynthesis. One moleculecreated from this element isomerises to create Stone-Wales defects, and that form is purified using amixture of DBU and trimethylbenzene. One form of this element is produced when cosmic rays bombardnitrogen. Chemical shifts between 0 and 200 ppm are observed in a type of NMR that observes a form ofthis element. Kroto, Smalley, and Curl found an unusual form of this element which forms a ball-likestructure. A sample of one type of this element is used in the precise definition of Avogadro's number,while another form of this element has a half-life of 5700 years. For 10 points, name this element whoseisotope with a mass number of 14 is used in radioactive dating.
An excited state of this element named for Hoyle is important in stellar nucleosynthesis.
carbon