Yes, a WhatsApp call can be traced. Anything can be traced. Some things are harder than others and tracing can be made more difficult by passing it through multiple systems but it can still be traced. In a call between two WhatsApp users, the WhatsApp system knows (logs) the information about the call.
When you call a dead phone does it ring?
Answer: A: With a dead battery it should not ring but it should go to voicemail directly.