The table shows the amount of radioactive element remaining in a sample over a period of time. Radioactive decay
Amount of radioactive sample(grams) Time (hours)
186.0 0
147.0 7
117.0 14
93.0 21
23.3 63

Part 1: What is the half-life of the element? Explained how you determined this.

Part 2: How long would it take 320 g of the sample to decay to 2.5 grams? Show your work or explain your answer.

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