CBSE Class 10 Science 2020 Outside Delhi Set 1

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Question : 17
Total: 30
Study the data of the following three categories A, B and C.
 Category  Name of the element  Atomic Mass
 A  Li
Na
K
  7
23
39
 B  N
P
As
  14
31
74
 C   B
Al Ga
 10.8
27
69.7
(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.
Solution:  
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