Correct Answer: The isotopes K-37 and K-42 have the same (2) bright-line spectrum
Reason:
K-37 and K-42 are isotopes of each other. Isotopes have same electronic distribution in their shell. The emission arises is due to deexcitation of electrons from excited state to ground state. Since, the electron distribution is same, both the isotopes i.e. K-37 and K-42, have same bright-line spectrum.
