1. How many molecules are in 0.500 mole of N2O5?
A. 1.20 X 1023 molecules
B. 3.01 X 1023 molecules
C. 6.02 X 1023 molecules
D. 3.01 X 1024 molecules

The problem here is that according to aufbau principle before 3d orbital 4s subshell comes.after filling 3p orbital with electrons you have 4 electrons left, you place two in 4s with opposite spin and the other two in 3d in any of its two orbitals of total five orbitals with the same spin.

Answer the molar mass of magnesium is 24.305g/mol.

Don’t know. don’t care.look it up on google

Van der waals forces are temporary electromagnetic forces established between uncharged atoms. some neutral molecules, when close together, can become temporarily “charged,” as electrons move around the atom. water is a polar molecule, the side of the molecule that the hydrogens bond to being more positive, and the opposite side bound to the lone pairs of electrons being more negative. this means that it participates in dipole-dipole interaction (non-polar exhibits dispersion forces), and it has the capacity for hydrogen bonding.