Question

Which of the following statements is not true about Dobereiner's law of triads?

• A. The law was applicable to all known elements
• B. Nitrogen family does not obey the law of triads
• C. Dobereiner's classification was not very useful
• D. The atomic mass of the central element of each triad was merely the arithmetic mean of of the atomic masses of other two elements

Answer 1

The correct option is A The law was applicable to all known elements

Döbereiner’s triads could find only three triads; .i.e total of 9 elements only but there were many more elements known at that time.

Therefore Dobereiner’s could not classify most of the elements known at that time.

Hence, the correct option is $A$