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Date November 2020 Marks available 1 Reference code 20N.1.SL.TZ0.12
Level Standard level Paper Paper 1 Time zone 0 - no time zone
Command term Question number 12 Adapted from N/A

Question

A substance in the gas state has a density about 1000 times less than when it is in the liquid state. The diameter of a molecule is d. What is the best estimate of the average distance between molecules in the gas state?

A.  d

B.  10d

C.  100d

D.  1000d

Markscheme

B

Examiners report

This question gives good discrimination at HL but less so at SL. Teacher comments felt that the question was too mathematical but it can be noted that it asks for an estimation of the average distance which is related to the cube root of the volume and 1000 is 103. At both levels option D proved a popular alternative suggesting that candidates were forgetting the cube root.

Syllabus sections

Core » Topic 3: Thermal physics » 3.2 – Modelling a gas
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