1. Why are electronegativity values helpful in determining if a bond is ionic, polar
covalent, or just covalent?
2. Why do atoms like carbon and nitrogen not like to make ions, while sodium and
chlorine do?
3. Why do you think ionic bonds are usually weaker than covalent bonds?

Amichelson interferometer operating at a 600 nm wavelength has a 3.02-cm-long glass cell in one arm. to begin, the air is pumped out of the cell and mirror m2 is adjusted to produce a bright spot at the center of the interference pattern. then a valve is opened and air is slowly admitted into the cell. the index of refraction of air at 1.00 atm pressure is 1.00028.how many bright-dark-bright fringe shifts are observed as the cell fills with air?