XPS analysis of this element must be careful not to confuse it with a similar binding energy peak from zinc. Sodium, oxygen, and this element make up Graham’s salt. The Gutmann–Beckett method uses NMR spectroscopy of this element’s 31 isotope. (10[1])A triphenyl derivative (10[2])of this element is found in Vaska’s complex and can also be used to create ylides (10[1])(“ILL-ids”) in the Wittig reaction. (10[1])Oxygen (10[1])and this element can form anions designated (10[1])as ortho or pyro, and also forms a triprotic acid. Alongside nitrogen (-5[1])and potassium, fertilizers report the content (10[1]-5[1])of this element. For 10 points, (10[1])name this element with red and white varieties (10[1])used to light matches. ■END■ (10[2])