Gold isotopes found in nature: 64Au, 66Au, 68Au,
70Au. Relative atomic mass of gold = 196.97
Calculate the percentage by mass of each isotope in natural gold?

Astudent carefully transfers 30 g of water and 30 g of alcohol in a glass tube, forming two layers and filling the tube completely. after sealing the tube, the student mixes the solutions, and notices a bubble that forms in the tube. what is the mass of the contents in the glass tube after mixing?