To find out the molecular weight of sodium fluoride (NaF), it is necessary to specify its constituent elements and atomic weights. The atomic weight of sodium (Na) is about 23, and the atomic weight of fluorine (F) is about 19.

Sodium fluoride is composed of one sodium atom and one fluorine atom, so its molecular weight is the sum of the atomic weight of sodium and fluorine, that is: 23 + 19 = 42.

From this, it can be seen that the molecular weight of sodium fluoride (NaF) is 42. This is based on the atomic weight of the element and the method of extrapolating the molecular weight of the substance.