Question

in figure skating competitions, the fourth - place finishers are often awarded medals made of pewter, a silvery - white alloy composed of tin and small amounts of antimony and copper. the atomic radii of tin, antimony, and copper are shown in the following table.
element atomic radius
sn 140 pm
sb 141 pm
cu 128 pm
based on the data in the table, which of the following diagrams best depicts the structure of pewter?
choose 1 answer:

Explanation:

Step1: Analyze alloy composition

Pewter is mainly tin with small amounts of antimony and copper.

Step2: Consider atomic - radius difference

The atomic radii of Sn (140 pm), Sb (141 pm) are close, and Cu (128 pm) is smaller. In an alloy structure, the main - component atoms (Sn) will form the bulk of the lattice, and the smaller atoms (Cu) and the atoms with a similar radius (Sb) will be in interstitial positions or substitute for Sn atoms in small amounts.

Step3: Evaluate diagrams

Diagram A shows a structure where Cu atoms (smaller) are interspersed among the larger Sn atoms, which is consistent with the composition and atomic - size relationship of pewter.

Answer:

A