Question

Up to which elements the Law of Octaves was found to be applicable?

• A. Oxygen
• B. Calcium
• C. Cobalt
• D. Potassium

Answer 1

The correct option is B

Calcium

Explanation for the correct option:

According to the law of Octaves, when the elements in the periodic table are arranged in the ascending order of their own atomic masses, it was observed that every eighth element were quite alike in their properties.

B) Calcium:

• As Calcium is not a heavy metal, and instead it is a lighter element having an atomic mass of $40u$ in the periodic table, the Law of Octaves held true only upto Calcium.
• In case of the elements following Calcium, every eighth element was not alike to the first element.

Explanation for the incorrect options:

A) Oxygen: Oxygen is a lighter element with an atomic mass of $16u$. It has properties similar to those of Sulphur.

D) Potassium: Potassium is also a lighter element having an atomic mass of $38u.$ It is similar in properties to Lithium and Sodium.

C) Cobalt: Cobalt is the twenty-seventh element in the Periodic table, and has an atomic mass of $59u$, thereby being a heavier metal than Calcium.

Hence option (B) is correct. The Law of Octaves was found to be applicable up to Calcium.