Q6 of 181 Page 281

A, B and C are the elements of a Dobereiner’s triad. If the atomic mass of A is 7 and that of C is 39, what should be the atomic mass of B?

Mass of B is 23. According to Dobereiner the atomic weight of middle element is nearly the same as average of the atomic weight of other two elements.


More from this chapter

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4

Rewrite the following statements after correction, if necessary:

(a) Group have elements with consecutive atomic numbers.


(b) Periodic are the horizontal rows of elements.


(c) Isotopes are the elements of the same group.

 5

Name the scientists who gave the following laws in the early classification of elements:

(a) Law of octaves


(b) Law of triads

 7

X and Y are the two elements having similar properties which obey Newland’s law of octaves. How many elements are there in-between X and Y ?

 8

What was the Mendeleev’s basis for the classification of elements ?