Question

The atoms of various isotopes of a particular element differ from each other in the number of:

• A. electrons in the outer shell only
• B. protons in the nucleus
• C. electrons in the inner shell only
• D. neutrons in the nucleus

Answer 1

The correct option is D neutrons in the nucleus

The atoms of various isotopes of a particular element differ from each other in the number of neutrons in the nucleus.
For example consider the isotopes of chlorine, ${}_{17}^{35}Cl$ and ${}_{17}^{37}Cl$.
${}_{17}^{35}Cl$ has 17 electrons, 17 protons and $35-17=18$ neutrons.${}_{17}^{37}Cl$ has 17 electrons, 17 protons and $37-17=20$ neutrons.