• # question_answer Which of the following describes an isotope with a mass number of 99 that contains 56 neutrons in its nucleus? A)  $_{56}^{99}Ba$                   B)  $_{56}^{43}Ba$C)  $_{43}^{99}Tc$                      D)  $_{43}^{56}Tc$

Given mass number (Z) = 99 no. of neutrons =56 $\therefore$ no. of protons = atomic number = 99 - 56 = 43 i.e. $_{43}T{{C}^{99}}$