在实验室中，用分液漏斗进行萃取操作时，振荡后需要_，以排出产生的气体，防止漏斗内压强过大。
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Correct answer
B. 放气
Principle or equation
分液漏斗振荡后，内部可能产生气体，需打开活塞放气以平衡内外压强。
Why this answer is correct
萃取振荡后，应及时打开分液漏斗的活塞（或旋塞）进行放气，确保安全。
Example
用CCl₄萃取碘水中的碘，振荡后打开活塞放气，再关闭活塞静置分层。
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