下表中列出了一些物质的熔点和沸点，根据表中数据回答下列问题：物质熔点沸点水0100萘80210水银

题文

下表中列出了一些物质的熔点和沸点（1标准大气圧下），根据表中数据回答下列问题：物质熔点（℃）沸点（℃）水0100萘80210水银-39357酒精-11778氮-210-196氧-268-183（1）表中所列物质在常温下属于固态的是________；氧在-145℃时所处的状态是______（2）要探究萘的熔化和沸腾过程中温度的变化，应选_______作温度计的测量物质。（3）如果在1标准大气压下用降温的办法从空气中提取氧和氮，那么温度下降时首先液化被分离出来的是                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  （4）1标准大气圧下，当温度为0℃时，水的状态（  ）A．一定是固态            B．一定是液态      C．一定是固液共存态       D．以上三种状态都有可能

题型：未知 难度：其他题型

答案

（1）萘 气态 （2）水银 （3）氧  （4）D

解析

（1）温度低于物质的熔点该物质是固态，常温低于80oC，萘是固态；-145℃高于氧的沸点-183oC，氧处于气态；（2）萘的熔点是80oC，沸点是210oC，应选水银温度计。（3）因为氧的沸点比氮高，采用降温法，温度首先低于氧的沸点，氧气先液化（如采用升温法则相反）被首先分离出来。（4）0oC时水的状态可能是固态（冰），也可能是液态（水），当然可能是固液共存（冰水混合物）状态。注意：是指水的状态，而不是问水是否结冰。

考点

据考高分专家说，试题“下表中列出了一些物质的熔点和沸点（1标准.....”主要考查你对 [凝固现象 ]考点的理解。

凝固现象

定义：物质从液态变成固态叫做凝固。凝固是熔化的逆过程。凝固放热。如水结成冰，由液态变成固态属于凝固现象。 凝固点：晶体开始凝固时的温度称为凝固点。同种晶体的熔点等于凝固点。 凝固条件：(1)达到晶体的凝固点。(2)不断放出热量。 生活中的凝固现象：水变成冰