Question

Dobereiner arranged similar elements in a group of three i.e. triads, on the basis of:

• A. Similar physical and chemical properties
• B. The atomic weight of the third element was approximately the arithmetic mean of the first two elements
• C. The atomic weight of the middle element was approximately the arithmetic mean of the other two elements
• D. Both (a) and (c)

Answer 1

The correct option is D Both (a) and (c)

Dobereiner arranged similar elements in groups of three which had similar properties (called triads) and the atomic weight of the middle element was approximately the arithmetic mean of the other two elements.
Example:
$Li(Atomicweight=7),Na(Atomicweight=23),K(Atomicweight=39)$
Here,$Naatomicweight=\frac{7+39}{2}=23$