A newly discovered element, X, has two naturally occurring isotopes. 93.5 percent of the sample is an isotope with a mass of 268
.9 u, and 6.5 percent of the sample is an isotope with a mass of 269.9 u. What is the weighted average atomic mass for this element?. . 268.5 u . . 269.0 u . . 269.4 u . . 269.8 u.
To calculate the average mass of the element, we take the summation of the product of the isotope and the percent abundance. In this case, it is 0.935 * 268.9 amu + 0.065* 269.9 amu. This is equal to an average mass of 268.965 amu.
Answer: Bubbles are evidence that a chemical reaction took place because cause formation of a precipitate. Bubbles are evidence that a chemical reaction took place because they indicate the formation of gas as a new product.
