Question

Statement: In Dobernier's classification of elements, the atomic mass of the middle element is equal to the average atomic masses of the extreme elements of a triad.

State whether the given statement is true or false.

• A. True
• B. False

Answer 1

The correct option is A True

Dobereiner classified the elements into triads (group of three). He made the groups such that the atomic mass of the middle element was the average atomic mass of the other two elements. This is Dobernier's law of triads.

$Li$, $Na$, $K$ is an example of Dobereiner's triad. Here, the average atomic mass of $Li$ and $K$ is equal to the atomic mass of $Na$

$\frac{(7+39)}{2}=23$

Thus, given statement is true.