Question

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	0	100
萘	80	210
水银	-39	357
酒精	-117	78
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

Answer 1

（1）萘 气态 （2）水银 （3）氧  （4）D

试题分析：（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-183^oC，氧处于气态；（2）萘的熔点是80^oC，沸点是210^oC，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）0^oC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。