How do i figure this out? What are they? How can i solve it?

Plzz i need help

How many valence electrons are in atom of radon?

Which of these is a density dependent factor? a. epidemic b. earthquake c. drought d. hurricane

The following questions a24 - a26 relate to 100 ml of 0.0150 m solution of benzoic acid (c6h3cooh). ka(c6h3cooh) = 6.4 x 10^-5. what is the ph of the solution after the addition of 1 x 10^-3 moles of naoh? you may assume no volume change to the solution upon addition of the naoh.