<u>Answer:</u> The correct answer is the mass number of the most common isotope of the element is 24.
<u>Explanation:</u>
We are given:
An element having atomic number 12 is magnesium and atomic mass of the element is 24.305
The image corresponding will be 
The number '24.305' is the average atomic mass of magnesium element.
Average atomic mass is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.
Formula used to calculate average atomic mass follows:

Average atomic mass of magnesium = 24.305 amu
As, the average atomic mass of magnesium lies closer to the mass of Mg-24 isotope. This means that the relative abundance of this isotope is the highest of all the other isotopes.
The 'Mg-24' isotope is the most common isotope of the given element.
Hence, the correct answer is the mass number of the most common isotope of the element is 24.
You should give answers since some people will just try and find any answer, which happened to me. So like if you have answers for the question just put them like A B C D kinda like true or false for others to know what they got instead of giving them more work, and then they just give you random answers.
Hot water rises cold water sinks. So the warm water will stay at the bottom. Transfer of heat through the molecules will make all the water boil
Negative because it'll have to gain an electron
Answer:
Freezing. When a liquid is cooled, the average energy of the molecules decreases. At some point, the amount of heat removed is great enough that the attractive forces between molecules draw the molecules close together, and the liquid freezes to a solid.
Note how temperature effects the motion of the atoms or molecules in a liquid. As the temperature of a solid, liquid or gas increases, the particles move more rapidly. As the temperature falls, the particles slow down. If a liquid is cooled sufficiently, it forms a solid.
<h3>I hope it helps you:)</h3>