SAT II 化学考试详解（3）

第二种题型. 对错问题（True/false and relationship questions in Part B）

在实际的SAT2考试中，这种类型的问题要求把答案写在标有“化学”的专用的答题纸上。第二种类型的题目从101道题目开始。每道题目的第一栏有一种表述，另一边的第二栏有另一种表述。你的首要任务是判断这些表述是否正确，并在答题纸上相应位置选择T或F；然后运用推理能力和对题目的理解判断两种表述是否存在因果关系。
下面是说明和例题
Part B
Directions: Every question below contains two statements, Ⅰin the left-hand column and Ⅱin the right-hand column. For each question, decide if statementⅠis true or false and if statementⅡis true or false and fill in the corresponding T or F ovals on your answer sheet. Fill in oval CE only if state Ⅱis a correct explanation of statement Ⅰ.

B 部分
说明：下面的每个问题包括两种表述，左栏的Ⅰ和右栏的Ⅱ。对于每一个问题，判断Ⅰ和Ⅱ的表述是否正确，并在答题纸上相应位置选择T或F。当Ⅱ是Ⅰ的正确解释时填涂CE。

Sample Answer Grid:
CHEMISTRY* Fill in oval CE if only Ⅱis a correct explanation of Ⅰ.

EXAMPLE

Ⅰ

Ⅱ

101.

When 2 liters of oxygen gas react completely with 2 liters of hydrogen gas, the limiting factor is the volume of the oxygen .

BECAUSE

The coefficients in the balanced equation of a gaseous reaction give the volume relationship of the reacting gases.

The reaction that takes place is
2H2 + O2 →2H2O
The coefficient of this gaseous reaction show that 2L of hydrogen react with 1L of oxygen, leaving 1L of unreacted oxygen. The limiting factor is the quantity of hydrogen.
The ability to solve this quantitative relationship shows that statement I is not true. However, statement II does give a true statement of the relationship of coefficients in a balanced equation of gaseous chemical reaction. Therefore, you should fill F in I and T in II.

Ⅰ

Ⅱ

101.

2升氧气与2升氢气充分反应，限制因素是氧气的量

因为

.配平的反应方程式的各个反应物的系数表明了参加反应的气体之间量的关系

反应的化学方程式为
2H2 + O2 →2H2O
气体反应的系数表明2L氢气与1L氧气反应，剩余1L氧气未参加反应。限制因素应是氢气的量。
定量结果表明I 是不正确的。但是，II 所表述的.配平的反应方程式的各个反应物的系数表明了参加反应的气体之间量的关系是对的。因此，在I中选择F，II中选择T。

第三种题型. 多项选择题（General multiple-choice question in Part C）

该题型通常为问题或者不完整表述，带有五个备选答案，你必须从中选出最佳答案。在有些题目中，要求选出不恰当的答案。这种问题包括大写的单词,例如NOT, LEAST, EXCEPT。
在有的问题中，会要求在图片，图表，数学表达式和文字表述之间建立联系。解决方法包括对已知信息的正确解读来解决科学问题。有时同一信息可以用来解答两个或更多的问题。

PART C
Direction: Every question or incomplete statement below is followed by five suggested answers or completions. Choose the one that is best in each case and then fill in the corresponding oval on answer sheet.

C部分
说明：下面的每个问题或不完整表述都带有五个备选答案。选出最佳答案并填写在答题纸的相应位置上。

EXAMPLE
If the molar mass of NH 3 is 17g/mol, what is the density of this compound at STP?

0.25g/L
0.76g/L
1.25g/L
3.04g/L
9.11g/L

The solution of this quantitative problem depends on the application of several principles. One principle is that the molar mass of a gas expressed in grams/mole will occupy 22.4L at standard temperature and pressure (STP). The other is that the density of a gas at STP is the mass of 1L of the gas. Therefore, 17g of ammonia (NH 3) will occupy 22..4L, and 1L is equal to 17g/22.4L or 0.76g/L. The correct answer is (B).

如果(NH 3)的分子质量是17g/mol, 在标准状况下这种化合物的密度是多少？