An atom has an average atomic mass of about 24.3 amu. What is the chemical

symbol for the atom? Consult the periodic table.

O Mg

O Cr

O Mn

O Ca

So first off, Look at the periodic table and find which of the elements has the amu of 24.3, amu is just the number below the element and the answer would be Mg

Answer: Option (a) is the correct answer.

Explanation:

Atomic number is the sum of only total number of protons present in an element. Whereas mass number is the sum of total number of both protons and neutrons present in an element.

So, for an atom with atomic mass 24.3 amu must have an atomic number as 12.

And, according to the periodic table only magnesium is the element which has an atomic number 12. As every element has different atomic number.

Chemical symbol which represents magnesium is Mg.

Thus, we can conclude that Mg is the chemical symbol for the atom which has an average atomic mass of about 24.3 amu.