DP Chemistry (last assessment 2024)

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Question 19N.3.hl.TZ0.4

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Date November 2019 Marks available [Maximum mark: 5] Reference code 19N.3.hl.TZ0.4
Level hl Paper 3 Time zone TZ0
Command term Outline, State, Suggest Question number 4 Adapted from N/A
4.
[Maximum mark: 5]
19N.3.hl.TZ0.4

Superconductors have no resistance below a critical temperature.

(a(i))

Outline how resistance to electric currents occurs in metals.

[1]

Markscheme

electrons collide with cations/positive ions ✔

(a(ii))

Suggest why the resistance of metals increases with temperature.

[2]

Markscheme

increased vibrations of «lattice» ions ✔
increased «probability of» collisions «between electrons and cations» ✔

NOTE: Accept “increases lattice vibrations” for M1.

(b)

State two differences between Type I and Type II superconductors.

[2]

Markscheme

Any two of:
Type I have sharper transitions to superconductivity «than Type II» ✔
Type I have lower critical/operating temperatures «than Type II» ✔
Type I have lower critical magnetic field «strength than Type II» ✔
Type I carry lower currents «than Type II» ✔
Type I are «pure» metals/metalloids AND Type II are alloys/metal oxide ceramics/perovskites/metallic compounds ✔
Type II exist in a mixed state/are partly permeable to the magnetic field AND Type I do not/are not ✔

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