Nimra M. answered 06/03/23
American Uni grad specializing in tutoring for languages, History, Eng
It's a long complicated process whenever empires end whether Roaman Empire or an ideology like communism. In the Soviet Union case, it happened just like it happened previously in many kingdoms, empires, and governments: the rebellion from inside and corruption brought political instability as Europe from outside kept knocking in until the German wall fell. Gorbachev's policy of slow democratization weakened communism and extreme poverty and political instability within the country eventually brought revolution.
Hope it gave you some idea. :) I'd say for the exam point of view focus on these keywords because otherwise it will be a long response.
keywords:
Tensions between Eastern and Western Europe
USA vs. Soviet Union tug of war to influence developing countries
Cuba Missile Crisis
Reagan era
Revolution
Fall of Berlin Wall
Gorbachev's democratization