Question

Which of the following sets of atomic masses do not correspond to Dobereiner's triad?

• A. 7, 23, 39
• B. 20, 38, 56
• C. 47, 91, 178
• D. 54, 95, 183

Answer 1

Answer: (C), (D)

The correct options are
C 47, 91, 178
D 54, 95, 183

The atomic mass of the middle element should be the average of the atomic masses of the first and third elements. In case of C and D options, the atomic masses do not correspond to that rule.