Question

give example of
a. Dobereiner's Triad
b. Two Alkali metals​

Answer 1

ᴇxᴀᴍᴘʟᴇ ᴏғ

ᴀ. ᴅᴏʙᴇʀᴇɪɴᴇʀ's ᴛʀɪᴀᴅ

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.

ʙ. ᴛᴡᴏ ᴀʟᴋᴀʟɪ ᴍᴇᴛᴀʟs​

The alkali metals are six chemical elements in Group 1, the leftmost column in the periodic table. They are lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).

Answer 2

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