True or False: Physics of Light?

True of False to each of the following?
1. Constructive interference occurs when two waves differ in phase by 180 degrees.

 2. Fluorescent lights are a source of coherent light.

3. A phase difference of 360 degrees is the same as a path difference of one wavelength.

 4. The reflected component of light traveling from one medium into another of lower refractive index will
under go a phase change of 180 degrees relative to the incoming light.

5. A laser can be source of monochromatic coherent light.

True