Why might some lead pipe crack if flexed as it ages?

• A. crystallizes
• B. corrodes
• C. anneals
• D. lengthens

Answer: (A)

When a metal ages under repeated stress, its internal structure can rearrange into crystalline grains. In lead, this crystallization creates new grain boundaries and concentrated stress points. Those hardened or differently oriented regions become initiation sites for cracks when the pipe is flexed, especially over time as stresses accumulate. So aging-induced crystallization best explains why lead pipe might crack with bending.

Corrosion involves chemical reactions with water, not the mechanical aging process described here. Annealing would soften the metal and relieve stress, usually reducing cracking risk rather than causing it. Lengthening isn’t a typical aging behavior for metal under flex.