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 18.90 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).

A solid gold cube contains 1.33×1029 atoms.  What is the vol…

A solid gold cube contains 1.33×1029 atoms.  What is the volume of the cube in cm3? The density of gold is 19.3 g/cm3. 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).