Why did the Qin Dynasty collapsed

Qin Shi Huang's son was killed, and the dynasty collapsed entirely.

Explanation:Upon the First Emperor's death, China plunged into civil war, exacerbated by floods and droughts. In 207 BCE, Qin Shi Huang's son was killed, and the dynasty collapsed entirely. Chaos reigned until 202 BCE, when Gaozu, a petty official, became a general and reunited China under the Han Dynasty.

xinhai revolution

Explanation:

because of xinhai revolution  (1911 revolution)

the answers are excess supply, and fall

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answer; andrew jackson approved nullification by signing it into law,and john calhoun opposed it saying it was unconstitutional;