Determine the nuclear composition (number of protons and neutrons) of the following isotopes. (a) chromium-52 protons neutrons (b) selenium-80 protons neutrons (c) molybdenum-98 protons neutrons (d) xenon-132 protons neutrons (e) ytterbium-174 protons neutrons

a) chromium-52 :  protons = 24, neutrons = 28

selenium - 80 :  protons = 34, neutrons = 46

molybdenum-98:  protons = 42, neutrons = 56

xenon-132:  protons = 54, neutrons = 78

ytterbium-174 :  protons = 70, neutrons = 104

Explanation:

Atomic number : It is defined as the number of electrons or number of protons present in a neutral atom.

Thus, number of protons = atomic number

Mass number is the number of the entities present in the nucleus which is the equal to the sum of the number of protons and electrons.

Mass number = Number of protons + Number of neutrons

a) chromium-52 :

Atomic number of Chromium is 24 hence number of protons  = 24

52= 24+ Number of neutrons

Number of neutrons = 28

b) selenium - 80 :

Atomic number of selenium is 34 hence number of protons  = 34

80 =  34 +  Number of neutrons

Number of neutrons = 46

c) molybdenum - 98 :

Atomic number of molybdenum is 42 is  hence number of protons  = 42

98 =  42 +  Number of neutrons

Number of neutrons = 56

d) xenon-132:

Atomic number of xenon is 54 hence number of protons  = 54

132 =  54 +  Number of neutrons

Number of neutrons = 78

e) ytterbium-174:

Atomic number of ytterbium is 70 and  hence number of protons  = 70

174 = 70 +  Number of neutrons

Number of neutrons = 104

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)