Question

What are the drawbacks of Newlands' law of octaves?

(A) The law of octaves was found to be applicable for elements with lower atomic masses.

(B) The position of hydrogen was not justifiable.

(C) Some unlike elements were placed in the same group.

• A. A, B
• B. A, B, C
• C. A only
• D. C only

Answer 1

The correct option is B A, B, C

The drawbacks of Newlands' law of octaves are-

1. The law of octaves was found to be applicable only till calcium. It was not applicable to elements of higher atomic masses.
2. The position of hydrogen along with fluorine and chlorine was not justified on the basis of chemical properties.
3. Newlands placed two elements in the same slot to fit elements in the table. He also placed some unlike elements under the same group. For example, cobalt ($\text{Co}$) and nickel ($\text{Ni}$) are placed in the same group as that of fluorine, chlorine and bromine. But cobalt and nickel have properties quite different from fluorine, chlorine and bromine. Similarly, iron which has resemblances with cobalt and nickel in its properties has been placed far away from these elements.