Isotopes are atoms having the same

The two stable isotopes of carbon present in naturally occurring carbon are

The electronic configuration of a divalent metal ion $M^{2+}$ is $2, 8, 14$ and its atomic mass is $58 \, a.m.u.$ What is the number of neutrons in its nucleus?

An ordinary oxygen sample contains:

An atom is composed of protons,neutrons,and electrons. If the mass of a neutron is halved and the mass of an electron is doubled,what will be the change in the mass of the nucleus of $_6C^{12}$?

If the mass attributed to a neutron were halved and that attributed to the electron were doubled,the atomic mass of $_6C^{12}$ would