Question

Citizens in Berlin began to tear down the Berlin Wall soon after
Boris Yeltsin became the leader of Russia.
Romania rejected Communism.
the Soviet Union officially dissolved.
East Germany opened its borders.

Answer 1

Do you want these put in chronological order or do you want each statement checked for accuracy? I'll give both briefly.

Chronological order (earliest → latest) with dates:
1. East Germany opened its borders / citizens in Berlin began tearing down the Berlin Wall — Nov 9, 1989.
2. Romania rejected Communism (Romanian Revolution; Ceaușescu overthrown) — December 1989 (around Dec 22–25, 1989).
3. Boris Yeltsin became leader of Russia (elected President of the RSFSR) — June 12, 1991 (took office July 1991).
4. The Soviet Union officially dissolved — December 26, 1991.

Accuracy notes:
- The statement "Citizens in Berlin began to tear down the Berlin Wall soon after Boris Yeltsin became the leader of Russia" is false — the Wall fell in 1989, well before Yeltsin became Russia's president in 1991.
- The other statements are essentially correct in timing as listed above.