Answer: 12 neutrons
Explanation: The mass number of an element tells us the number of protons AND neutrons in an atom (the two particles that have a measurable mass). Sodium has a mass number of 23amu. Since sodium has 11 protons, the number of neutrons must be 23 – 11 = 12 neutrons.
The correct answer to this item is letter
C. convection in earth's mantle
Convection currents move tectonic plates when the rising mantle creates heat inside. The radioactive decay of several substances is responsible for the creation of the convection currents.
That would be the proton. The number of protons in the nucleus determine which element it is and its properties.