-A student would like to prepare 250 mL of 0.25 mol L lead(II) nitrate, solution.
Calculate the mass of lead(II) nitrate required to prepare the solution.

20.68

Am I right??

I solved it but exactly i donot know I think eq. wt of lead nitrate is 331

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.