Question

A=20 B=120. c=? find dobereiner triad​

Answer 1

According to Dobereiner :
The atomic mass of the middle elements is roughly the mean of the other two elements of their atomic mass.

So,

Here ,

The other two elements is "20"and" C"

Middle elements is 120.

Their mean is =

20+C/2=120

=>20+C=240

=>C=240-20

=>C=220

so, the value of" C" is 220