As per Mendeleev’s prediction, the atomic mass of eka-aluminium was:
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 68.
As per Mendeleev's prediction, the atomic mass of eka-aluminium, which was later identified as gallium (Ga), was 68. Mendeleev, while formulating his periodic table, predicted the properties of elements that had not yet been discovered. He named this missing element "eka-aluminium" because it was placed below aluminium in his periodic table. When gallium was eventually discovered in 1875 by Lothar Meyer and Paul-Émile Lecoq de Boisbaudran, its atomic mass was found to be approximately 69.72, confirming Mendeleev's prediction.