Question

The three imaginary elements X, Y and Z represent a Dobernener's triad. If the atomic mass of element X is 14 and that of element Y is 46, then the atomic mass of element Z will be:

(a) 28
(b) 60
(c) 78
(d) 72

Answer 1

(c) 78
The atomic mass of the element Z is 78.
According to  Dobereiner's law of triads, atomic mass of `Y=(X+Z)/2`
Substituting the atomic masses we get:

`46=(14+Z)/2`

92 = 14+Z

Therefore, Z = 78