Think of the phrase ""iron curtain. "" What does the word ""iron"" make you think of? something hard something cold something impenetrable.

impenetrable

Explanation:

something impenetrable.

Explanation:

the curtains wouldn't be hard or cold they are made to block out light so the would be impenetrable

I could honestly be wrong on this but, I hope I at least helped in some way.
#2 - spoke the same language
- celebrated same holidays and traditions
- comfort to live with similar people
#3 -Long hours and not so good pay.
#4 - Wooden houses on the Mississippi shore that were crowded and many poor immigrants resided there. Houses would float down the river when it flooded.
#5 - went undercover in factories- wrote articles
- ran for political office
- public speaker, motivated workers to go on strike
#6 - The population to very few, to over 25,000.
#7 - Dangerous
- Long Hours
- Bad Pay
#8 - They hated their work conditions.
#9 - More and more people wanted to live here because of the soil and other natural resources.
#10 - -good moral character
-English or U.S. history or government tests
-by birth
-live here for five years 
-have to be over 18