1) The nucleus of a certain atom has a radius of 4.0 × 10-15 m. An electron orbits the nucleus at a radius of 1.5 × 10-10 m. Imagine the electron orbit is on the surface of a sphere and that the shape of the nucleus is spherical. Approximately how many nuclei would fit into the sphere on which the electron orbits?
A) 5.3 × 1013
B) 4.9 × 1011
C) 1.4 × 109
D) 7.5 × 107
E) 3.8 × 104
2) AN object has a charge of -2 microC. How many electrons must be removed so that the charge becomes +3 microC?
3) Calculate the charrge of 1.25 moles of sodium ions (a sodium ion consists of 11 protons and 10 electrons.