15. a- if an Lithium (atomic number 3) atom has a -2 charge, how many electrons does it have? - Why do you do it this way? - Is this an anion or a cation? d- Why? A-
B-
C-
D-
PLEASE HELP THANK YOU :)

Why do scientists believe that light is made of streams of particles? scientists believe that light is made of streams of particles because only the presence of photons can explain phenomena observed during experiments on the photoelectric effect. these observations include only some frequencies of light causing the ejection of electrons, no time gap existing between light striking a metal and electrons being ejected, and intensity having no effect on the kinetic energy of the ejected electrons.

Astudent pushes on a 20.0 kg box with a force of 50 n at an angle of 30° below the horizontal. the box accelerates at a rate of 0.5 m/s2 across a horizontal floor. what is the value of the normal force on the box? 200 n 243 n 156 n 225 n

Which notation is used to represent an alpha particle? a. b. c. d.