Question

In the long form of periodic group lanthanides are placed in the:

• A. $2^{nd}$ period
• B. $5^{th}$ period
• C. $6^{th}$ period
• D. $7^{th}$ period

Answer 1

The correct option is C $6^{th}$ period

The lanthanide elements are the group of elements with atomic number increasing from 57 (lanthanum) to 71 (lutetium). They are termed as lanthanides because the lighter elements in the series are chemically similar to lanthanum.