Perestroika, meaning 'restructuring,' was a policy introduced by Mikhail Gorbachev in the 1980s to reform the Soviet economic and political system. It aimed to introduce limited market-like reforms, increase the efficiency of state enterprises, and decentralize economic decision-making. This was intended to revitalize the stagnant Soviet economy, though it ultimately contributed to the political instability that led to the dissolution of the USSR.

At the founding of the United Nations, the Soviet Union successfully negotiated for the Ukrainian SSR and the Byelorussian SSR to have their own seats alongside the USSR itself. This brought the total number of Soviet-aligned seats to three, but specifically, two individual Union Republics were granted separate membership. This was a strategic move to increase Soviet influence in the General Assembly.

The term 'Buran' refers to a severe, violent blizzard characterized by high winds and drifting snow, common in the Russian steppes. While the source answer defines it as 'Firestorm,' this is linguistically debated as the term is primarily meteorological. However, in the context of Soviet technology, the 'Buran' was also the name of the Soviet space shuttle, symbolizing power and intensity, which may explain the 'Firestorm' translation in this specific context.

The Soviet Union officially ceased to exist on December 26, 1991, following the resignation of Mikhail Gorbachev and the formal dissolution of the state. While the source answer identifies 1990, the consensus among historians is that the collapse occurred in 1991. The source answer is factually incorrect regarding the final year of the Soviet state.

The Chairman of the Presidium was often referred to as the head of state, though real power frequently resided with the General Secretary of the Communist Party. The source identifies this role as the 'Executive head of the state', which may be contested by scholars who view the position as largely ceremonial or titular compared to the Party leadership.

In the Soviet administrative hierarchy, the appointment of local procurators at the area, district, and city levels was vested in the respective supreme soviets of the administrative divisions. This structure was designed to integrate the judicial and prosecutorial functions into the broader legislative and administrative apparatus of the Soviet state, ensuring local oversight and alignment with central directives.

Under the provisions of the 1936 Soviet Constitution, the legislative structure included the Supreme Soviet, which consisted of two chambers. Autonomous regions were granted specific representation within this body to ensure the inclusion of various ethnic and regional interests. The allocation of five deputies per autonomous region was a mechanism to maintain the appearance of federal representation within the centralized legislative framework of the Soviet Union.

The USSR was formally dissolved on December 26, 1991, following the Belovezha Accords and the resignation of Mikhail Gorbachev. This event marked the end of the Cold War and the collapse of the Soviet communist system, leading to the independence of fifteen former Soviet republics. The dissolution was the culmination of years of political and economic instability within the Soviet bloc.

The Chairman of the Presidium of the Supreme Soviet was vested with the constitutional authority to grant pardons. This power was a formal prerogative of the head of state, allowing for the mitigation of sentences and the exercise of clemency, reflecting the centralized nature of executive authority in the Soviet Union.

Attributing the collapse of the USSR solely to Mikhail Gorbachev's policies (Glasnost and Perestroika) is historically reductive. While his reforms were catalysts, the disintegration was the result of a complex interplay of factors, including long-term economic stagnation, the rise of nationalist movements in the republics, the burden of military spending, and systemic political rigidity. Gorbachev's actions were a response to these pre-existing structural crises rather than the singular cause of the collapse.