What is the most useless element periodic table?

Answer 1

Protactiniumand Francium have no known uses outside the lab. Protactinuium is an unwanted natural byproduct of uranium decay. Francium is radioactive and very unstable.

Answer 2

There isn't a universally agreed upon answer to this question, as the usefulness of an element can vary depending on context and application. However, some may consider francium to be one of the least useful elements as it is extremely rare, highly radioactive, and has no significant practical applications due to its short half-life and scarcity.