Question 19M.3.hl.TZ1.a
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.3.hl.TZ1.a |
| Level | hl | Paper | 3 | Time zone | TZ1 |
| Command term | Deduce | Question number | a | Adapted from | N/A |
Physical properties of elements vary according to atomic number. Sections 6 to 9 of the data
booklet list some of these properties.
Melting points and boiling points of elements 1 to 95
Deduce, giving a reason, the group of elements in the periodic table most likely to undergo sublimation.
[2]
group 18/noble gases [✔]
smallest difference between melting and boiling points
OR
weakest intermolecular forces «in that period» [✔]
Note: Accept “group 17/halogens”.
Most candidates correctly identified the group of elements most likely to undergo sublimation but did not score for the reason as they referred to low melting and boiling points, rather than the smallest difference between these temperatures. There were several G2 comments that “the group of elements” was a confusing requirement as elements could be grouped in many ways, including for instance, from B to Ne. The Chemistry Guide clearly states that a group on the periodic table refers to a vertical column of elements. A few complaints were received about the inclusion of a question on sublimation, but the question was designed to make candidates think, and did not require knowledge of phase diagrams.
