Which is the correct symbol for the atom with 42 protons and 49 neutrons?

Explanation:

Number of protons present in an atom are actually the atomic number of atom. Each element will have different atomic number.

Hence, each element is different in nature. On the other hand, atomic mass is the sum of number of protons and number of neutrons present in an element.

For example, Molybdenum is the element with 42 protons and 49 neutrons. Molybdenum is represented by the symbol Mo.

Therefore, we can conclude that Mo is the correct symbol for the atom with 42 protons and 49 neutrons.