有條關於bronze同copper既問題

The answer is D.

Copper is a pure metal. In copper, all the atoms are identical, and thus the atoms are packed regularly. When a force is exerted, layers of atoms can slip into each other readily. This explains the ductility and malleability of metals.

Bronze is the alloy of copper and tin. When tin atoms of different size are introduced, the metal atoms are packed more irregularly. Therfore, when a force is exerted, layers of atoms slip into each other less readily. This increases the strength of bronze.

2009-08-19 18:23:33 補充：
你想像一下便可以知道。全部同一大小圓球形排在一起，圓球形由一層滑至另一層比較容易。但加入一些大小不同的圓球形，滑動便比較困難了。