Question 13 Answer and Explanation _ACT April 2017 Form 74F Science Section

Passage II

A teacher provided the table below to the students in a science class. The table gives 5 properties for each of Samples A-H. The students were told to assume that each sample is a completely solid cube composed of a single hypothetical pure substance.

The teacher asked each of 4 students to explain how these data could be used to predict which samples are composed of the same substance.

Student 1

If 2 samples have the same values for all 5 properties, they are composed of the same substance. If 2 samples have different values for any of the 5 properties, they are composed of different substances.

Student 2

If 2 samples have the same values for any 3 or more of the 5 properties, they are composed of the same substance. If 2 samples have the same values for fewer than 3 of the properties, they are composed of different substances.

Student 3

If 2 samples have the same mass, volume, and density, they are composed of the same substance. If 2 samples have different values for any of these 3 properties, they are composed of different substances. Neither melting point nor boiling paint, by itself, can distinguish between substances.

Student 4

If 2 samples have the same density, melting point, and boiling point, they are composed of the same substance. If 2 samples have different values for any of these 3 properties, they are composed of different substances. Neither mass nor volume, by itself, can distinguish between substances.

13. Suppose that the temperature of Sample D is increased to 890°C at 1 atm of pressure. Will the sample’s density be lower than or higher than it was at 20°C and 1 atm ?

A. Lower; Sample D will be a gas, and gases generally have lower densities than do solids.

B. Lower; Sample D will be a liquid, and liquids generally have lower densities than do solids.

C. Higher; Sample D will be a gas, and gases generally have higher densities than do solids.

D. Higher; Sample D will be a liquid, and liquids generally have higher densities than do solids.

Answer and Explanation

Your Answer is

Correct Answer is A

Explanation

Looking at the table, the boiling point of sample D is 885°C. The temperature given in the title is 890°C, which exceeds the boiling point. At this time, sample D is no longer a solid, but a gaseous state, so the density should be even smaller.