试题与答案

如图所示是某物理小组在观察“水的沸腾”实验中的情景. (1)请指出他们在实验中

题型:问答题

题目:

如图所示是某物理小组在观察“水的沸腾”实验中的情景.

(1)请指出他们在实验中操作错误之处(举出一个即可):______.

(2)在纠正错误后他们继续实验,观察到水沸腾时的现象如图中的 ______图,水沸腾时吸收热量,温度 ______.(选填:“升高”、“不变”、“降低”)

(3)实验测出水的沸点为99℃,说明当时的气压 ______1标准大气压(选填:“>”、“<”、“=”)

答案:

(1)在读数时,视线应与液柱的上表面相平,而图中俯视了.

故答案为:读数时,视线未与液柱的上表面相平.

(2)沸腾时,有大量气泡产生,气泡在上升过程中体积增大.所以乙图是沸腾时的现象.水沸腾时要不断吸热,但温度不变.

故答案为:乙,不变

(3)气压越高,液体的沸点越高.标准大气压下水的沸点是100℃,而实验中水的沸点是99℃,所以当时气压低于标准大气压.

故答案为:<.

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