Which of the following statements are correct? (a) A substance will emit radiation at a particular wavelength only (b) All substances emit radiation (c) Only some substances emit radiation (d) Bodies black in colour are known as black bodies

Answer: b) All substances emit radiation

Explanation: This is a universal statement that all bodies emit radiations. The radiations are usually in the form of electromagnetic radiations that are being emitted in accordance with temperature that varies from body to body. Even human bodies along with any other body emit radiations These radiations are absorbed by the black body. Therefore the correct option is option (b).