Answer:
76.1 amu
Explanation:
Let us recall that isomers refer to two different compounds with the same molecular formula but different atom to atom connectivity and different chemical properties. When two compounds are isomers, we can essentially represent them with exactly the same molecular formula.
Now propane-1,2-diol and propane-1,3-diol are both represented by the molecular formula C3H8O2 since they are isomers of each other. When two compounds have the same molecular formula, they must essentially have the same molecular mass. Hence the molecular mass of propane-1,3-diol is also 76.1 amu.
