Consider the element indium,atomic number 49,atomic mass 114.8 g.The nucleus of an atom of indium-112 contains
A)49 protons,63 neutrons,49 electrons
B)49 protons,49 neutrons
C)49 protons,49 alpha particles
D)49 protons,63 neutrons
E)49 protons,112 neutrons

Question

Quizplus · Accepted Answer

The atomic number of an element indicates the number of protons. In this case, indium has an atomic number of 49, which means it has 49 protons in its nucleus. The atomic mass is the sum of protons and neutrons in the nucleus. Since the atomic mass of indium is 114.8, it means that it has (114.8 - 49)= 65.8 neutrons. Therefore, the nucleus of an atom of indium-112 (which is less than the atomic mass) should have fewer neutrons than the stable isotope, i.e., 63 neutrons. Therefore, the correct option is D) 49 protons, 63 neutrons.

Consider the Element Indium,atomic Number 49,atomic Mass 114