Question

In $4^{\text{th }}$ period of periodic table, how many elements have one or more $4d$ electrons?

• A. 2
• B. 0
• C. 13
• D. 6

Answer 1

Answer: (B)

$4^{\text{th }}$ period comprises of $4s,3d$ and $4p$.

$4d$ elements will lie in $5^{\text{th }}$ period