How many protons are in a radium-226 nuclide?
a. 88
b. 138
c. 226
d. 314

Option (A) is the correct answer.

Explanation:

Atomic number is defined as the sum of total number of protons present in an element.

Whereas mass number is defined as the sum of total number of protons and neutrons present in an atom.

Also, when an atom is neutral in nature then its number of protons are equal to the number of electrons.

For example, atomic number of radium is 88 and mass number is 226.

Hence, number of neutrons can be calculated as follows.

                 Mass number = no. of protons + no. of neutrons

                            226 = 88 + no. of neutrons

                     No. of neutrons = 226 - 88

                                                 = 138

Thus, we can conclude that there are 88 protons present in radium-226 nuclide.

it is the most commonly accepted one