BEANTWORTEN SIE FRAGEN - English

I understand the difference between Proper noun and Common noun, but:

Is concrete noun a common noun?

Is abstract noun a common noun, but not a concrete noun?

Are collective noun and compound noun a concrete noun?

People say that a concrete noun can be felt with all 5 senses, but electricity is concrete noun and break the rule. I don't understand!

Maybe it's simpler, but I don't understand.