An unknown element has two naturally occurring isotopes with…
An unknown element has two naturally occurring isotopes with masses 18.00 amu (A) and 21.00 amu (B) and has an atomic mass of 19.90 amu. What’s the natural abundance of isotope A (%)? Mark your answer next to words “Final answer is”. You must follow significant figure rules. You must show your work here to receive any credit (you may receive 0 points for only showing your final answer).