Can a black labrador retreiver have white chest?

No, a purebred black Labrador retriever should not have a white chest. According to the breed standard set by the American Kennel Club (AKC), a black Labrador retriever should have a solid black coat without any white markings. The only exception to this rule is a small white spot on the chest, known as a "tuxedo mark," which is sometimes seen in show-quality dogs. However, even this white spot is not considered desirable and is not preferred in the show ring.