HQ 2.14 Homework . Unanswered The atomic mass of an element is the weighted average mass of: Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a All of an element's naturally occurring isotopes b Just the element's least abundant isotopes Just the element's most abundant isotope Why (evens) HQ 2.16 Homework Unanswered 3/15 answered What is the atomic mass number of an element that has 19 protons, 19 electrons, and 20 neutrons? Type your numeric answer and submit Unanswered . 1 attempt left 0 HQ 2.18 Homework Unanswered Which symbols represent atoms that are isotopes of each other? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer a 14C and 14N b 1311 and 1311 160 and 180 d 222 Rn and 222 Ra Unanswered . 1 attempt left The Periodic Table & 8 7 9 0 5