This question has two parts.
This excerpt describes the reasons Russians migrated to other Soviet republics during the middle of the twentieth century.
The Soviet Union, the world's first communist country, was made up of Russia as well as the territory of 14 other present day countries. The U.S.S.R. existed from 1922 to 1991. Many Russians moved to other Soviet republics between 1950 and the mid-1970s. For example, migrants from Russia moved to Ukraine and Belarus during the 1950s to rebuild cities damaged during World War II. Russian farmers moved to Kazakhstan to grow crops on available land. Many Russians moved to republics in Central Asia to work in newly built factories. After 1991, the communist party lost power, and the Soviet Union broke up into a number of independent states, leaving many ethnic Russians living outside Russia.
Based on the excerpt, for what reason did many ethnic Russians move to other Soviet republics during the middle of the 20th century?