1. Can you change FILE FORMAT just by changing it's name?
No, You must SAVE the file AS whatever format you choose.
2. How many colors are in the following Color Modes?
RGB: 16.7million
INDEXED COLOR: 256 or Less
GREYSCALE: 256
BITMAP: 2
3. What happens to the (uncompressed) FILE SIZEas you change the COLOR MODES?
The file size get smaller depending on the amount of colors used in the image.
4. What happens to the visual quality of images as you REDUCE the number of colors by changing the color mode?
The Image file size will get small and depending on the file type, the image might worse in quality.
5. What is a good reason to convert PSD files to JPG?
To send files via email, to upload onto the internet.