Which scientist discovered the two radioactive elements radium and polonium?

This is for my 8th grade science class, i really don’t understand. can someone me? , lol.

What’s #16 asking and how do i solve it?

If state law mandates that elevators cannot accelerate more than 2.40 m/s2 or travel faster than 14.8 m/s , what is the minimum time in which an elevator can travel the 373 m from the ground floor to the observatory floor? ?