Question 4 What is the standard Hz rate (cycles per second) in the US? 60 Hz 20 Hz 50 Hz 80 Hz

The standard in the United States is 120-volt and 60Hz AC electricity.

i guess that visual aids present persuasive examples to what you are presenting, some factors would be theme (does it fit with the color, information, what you are presenting), size (can you see it, is it a big enough span of data/information), and overall look of the visual aid.

hope this : )