Question

Which of the following will definitely emit only $\gamma$-radiation?

• A. ${}_{92}^{238}\text{U}$
• B. ${}_6^{14}\text{C}$
• C. ${}_1^3\text{H}$
• D. ${}^{60m}\text{Co}$

Answer 1

The correct option is D ${}^{60m}\text{Co}$

${}^{60m}\text{Co}$ exists in high energy state (excited) and decays by emission of $\gamma$ ray with a half life of 10.5 min to the lowest energy state (ground state).