In each of the triads how many elements were identified by Doberenier?

Correct option is B

The correct answer is (b) 3
Dobereiner, a German chemist, observed that certain groups of three elements, called triads, had similar chemical properties. In each triad, the properties of the middle element were the average of the other two. This was an early approach toward organizing elements and understanding their relationships.
Information Booster

•  Dobereiner’s work focused on triads, where each group consisted of 3 elements with similar characteristics.
  
• The middle element in a triad showed properties that were the average of the first and third elements.
  
•  An example of a Dobereiner triad is Lithium, Sodium, and Potassium, where Sodium’s properties are intermediate between the other two.
• His observations led to the early development of the Periodic Table, influencing Mendeleev's later work.
  
•  The triad concept highlighted the periodic nature of element properties, an idea that was later refined and expanded.