The fluorescence of a CFP solution is quenched with a 30 mM solution of YFP, where the observed fluorescent lifetime is 0.5 s and the quenching rate is 43.0 M-1 s-1. Use the Stern-Volmer equation to find the ratio of non-quenched to quenched fluorescence, and then use the inverse of this ratio to calculate the percentage change in fluorescence upon quenching.

An unknown substance is a white solid at room temperature and has a melting point of 78 °c. which of the following substances is most likely to be the identity of the unknown sample? a. naphthalene, a molecular solid with the formula c10h8 b. silica, a network solid held together by covalent bonds with the formula sio2 c. calcium chloride, an ionic compound with the formula cacl2 d. water, an molecular compound with the formula h2o