Question

In Dobereiner classification of elements, the atomic weight of the middle element is equal to the ________ of the extreme elements of a triad.

• A. sum
• B. average
• C. difference
• D. fraction

Answer 1

The correct option is B average

In Dobernier classification of elements, the atomic weight of the middle element is equal to the average of the extreme elements atomic weight of a triad.

Example Atomic weight

Lithium--------- 7

Sodium--------- 23

Potassium------- 39

Average of atomic weights of lithium and

Potassium = $\frac{7+39}{2}=\frac{46}{2}$ =23

23 is the atomic weight of sodium.