Question

CBSE 2020 BOARD
(i) From the given three categories A, B and C, pick the one which
forms Dobereiner's Triads.
(ii) Why did Mendeleev placed elements of category A, B and C in three
different groups ?
(iii) Is Newland law of octaves applicable to all the three categories ?
Give reason to justify your answer.
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Answer 1

Answer:

i) A

ii) Mendeleev placed the elements according to their halides and oxides formation.

iii) No Newland law of octaves is not applicable because in the three categories every eighth element will not show same property same as first.. Newland octaves law is applicable only elements upto calcium....