1. identify causes for post-world war ii prosperity and its effects on american society
2. explain how post-world war ii prosperity differed by ethnic group and social class

The following are the answers to your question:  

1. after the WWII, military spending decreases, and government creates some economic support programs that help Americans and business causes consumer spending increase. American started buy more goods because they have more money to spend

2. prosperity is occured in the city and for white and educated people nor for minority like African American, Mexican immigrants, and other minority groups. one out of five who live below powerty line which mean they are poor people  

Hope my answer would be a great help for you.