How many protons and neutrons are in an atom of Mo-94?

This is a great example of a question that actually provides you with the answer.

The quick answer here is that there are #94# protons and neutrons in a molybdenum-94 isotope, #""^94"Mo"#.

That is the case because an element's isotopes are distinguished using their mass number, which is added to the name of the isotope using a hypen.

As you know, the mass number, #A#, tells you the number of nucleons present in the nucleus. A nucleon is simply a proton or a neutron.

This means that the mass number of a given isotope essentially tells you how many protons and neutrons are present in its nucleus.

In your case, molybdenum-94 has a mass number of #94#, which means that it contains #94# protons and neutrons in its nucleus.

To find the specific number of protons and of neutrons, grab a periodic table and look for molybdenum, #"Mo"#. You'll find the element listed in period 5, group 6.

Its atomic number, #Z#, which tells you how many protons are present in the nucleus, is equal to #42#. This means that the nucleus of any isotope of molybdenum will contain #42# protons.

This leaves you with

#"no. of neutrons" = A - Z#

#"no. of neutrons" = 94 - 42 = "52 neutrons"#