A student is working with four different solid substances: sodium (Na), calcium (Ca), copper (Cu), and iodine (I). Which substance is most likely to break easily into many smaller pieces?

Iodine is a molecular solid, and its molecules are held together by relatively weak attractions. When a solid iodine crystal is struck, it tends to fracture rather than bend. Sodium, calcium, and copper are metals, which are generally malleable and more likely to deform than shatter. Therefore, iodine is most likely to break into many smaller pieces.

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