Which statement best describes soft solder?

• A. It forms a strong joint with low electrical resistance.
• B. It melts at very high temperatures.
• C. It corrodes rapidly in air.
• D. It bonds only to copper.

Answer: (A)

Soft solder is a filler metal used to join electrical components. It has a low melting point, so it can be melted and flowed into joints without applying extreme heat that could damage parts. When it wets the surfaces and flows into gaps (aided by flux), it forms a metallurgical bond that provides a good electrical path, giving low resistance across the joint. That combination—low melting temperature, good wetting, and an electrical bond—is why it’s chosen for electronics.

The other statements don’t fit because soft solder does not melt at very high temperatures, it doesn’t corrode rapidly in normal air conditions (flux and oxide layers help protect the joint during use), and it can bond to many metals, not just copper.