6. in the 1920’s the first red scare was the fear of what? why?

The first red scare of the 1920's was caused by a variety of reasons including fear and suspension of immigrants and foreigners fueled by World War 1 propaganda techniques, widespread labor unrest, the rising tide of Communism and a series of terrorist attacks in the homeland. 

(credits to american-historama.org)

hope this helped, God bless!