Question

Refer to the Periodic table and identify a highly reactive metal in the sixth period.

• A. $Cs$
• B. $W$
• C. $Os$
• D. $Ir$

Answer 1

The correct option is A $Cs$

As we move from left to right along a period, metal activity decreases. So here "$Cs$" (alkali metal) is a highly reactive metal in the sixth period.

All others are d-block elements so they are less reactive than $Cs$.