Question
The mass spectrum for an unknown element is shown above. According to the information in the spectrum, the atomic mass of the unknown element is closest to
A 90amu
B 91amu
C 93amu
D 94amu
▶️Answer/Explanation
Ans:B
The relative abundances of the isotopes with atomic masses 90 and 92 have a weighted average that would be less than 91. That result with the influence of the mass and abundance of the isotope with atomic mass 94 would result in a weighted average closer to 91 than to 93.
Question
The mass spectrum represented above is most consistent with which of the following elements?
A Eu
B Gd
C Tb
D Dy
▶️Answer/Explanation
Ans:B
The average atomic mass of Gd is close to 157amu. The relative abundance and masses of the isotopes shown in the mass spectrum predict an average atomic mass close to 157amu.
Question
The mass spectrum of an average sample of a pure element is shown in the figure above. Which of the following is the identity of the element?
(A) Y
(B) Zr
(C) Nb
(D) Th
▶️Answer/Explanation
Ans:D