CHEMISTRY · Single correct · A Level · Chemistry · Atomic structure · Atomic structure
Problem
An element may occur as different isotopes. Element X has three isotopes with mass numbers 20, 21 and 22. The fractional abundances are 0.90, 0.01 and 0.09 respectively. The average atomic mass of the element is
(1) 20.19
(2) 19.34
(3) 20.8
(4) 21.28