Question

Identify the set of elements that will form Dobereiner triad.

options

Lithium, sodium, potassium
Nitrogen, phosphorus, arsenic
Helium, neon, argon
Helium, hydrogen, potassium​

Answer 1

Answer:

He found that the masses of the three elements from the pattern like other triads. ... Some elements were missing and the law did not seem to hold for elements heavier than calcium.

Explanation:

Triad, in chemistry, any of several sets of three chemically similar elements, the atomic weight of one of which is approximately equal to the mean of the atomic weights of the other two. Such triads—including chlorine-bromine-iodine, calcium-strontium-barium, and sulfur-selenium-tellurium—were noted by the German chemist J.W. Döbereiner between 1817 and 1829. The triad was the earliest atomic-weight classification of the elements

Answer 2

first one.lithium,sodium,potassium