DP Chemistry (last assessment 2024)

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Question 17N.3.sl.TZ0.4b.i

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Date November 2017 Marks available [Maximum mark: 1] Reference code 17N.3.sl.TZ0.4b.i
Level sl Paper 3 Time zone TZ0
Command term Outline Question number b.i Adapted from N/A
b.i.
[Maximum mark: 1]
17N.3.sl.TZ0.4b.i

It is wise to fill dental cavities before irreversible tooth decay sets in. An amalgam (alloy of mercury, silver, and other metals) is often used although many prefer a white composite material.

(b.i)

Outline why an alloy is usually harder than its components by referring to its structure.

[1]

Markscheme

difference in ionic/atomic radius prevents layers sliding over each other

Accept “difference in diameter/packing of cations prevents layers sliding over each other”.

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