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Science · 2022 · 3 marks
CBSE 2022 · Region 2 · Set 1 · Q8
(a)State Newland Law of Octaves. $\displaystyle \mathbf{1}+\mathbf{1}+\frac{\mathbf{1}}{\mathbf{2}}+\mathbf{1} \frac{\mathbf{1}}{\mathbf{2}}=\mathbf{3}$(b)With an example, explain Dobereiner's Triads.(c)List one limitation each of both the attempts mentioned in 'a' & 'b'.
(a)
State Newland Law of Octaves. $\displaystyle \mathbf{1}+\mathbf{1}+\frac{\mathbf{1}}{\mathbf{2}}+\mathbf{1} \frac{\mathbf{1}}{\mathbf{2}}=\mathbf{3}$
(b)
With an example, explain Dobereiner's Triads.
(c)
List one limitation each of both the attempts mentioned in 'a' & 'b'.
Marking-scheme solution
(a) "When the elements are arranged in the order of their increasing atomic masses, then every eighth element has properties similar to the first element."
(b) When the elements of a triad are arranged in the order of their increasing atomic masses, the atomic mass of the middle element is equal to the average of the atomic masses of other two elements.
Examples:
Li Na K
Ca Sr Ba
Cl Br I
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CBSE Class 10 Science past-paper question from the 2022board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.