Question

P,Q and R are any three elements in Dobereiner's classification.When can these three elements constitute a traid if their atomic masses are 87.6 , 40.1 and 137.3 respectivety.

Answer 1

87.6=strontium,40.1=calcium,137.3=barium

atomic mass of an middle element was approximately equal to the mean of the atomic masses of two elements

strontium=40.1+137.3÷2=87.6