Explanation:


The sum of the atomic mass of all atoms present in one molecule of a molecular compound is referred to as the molecular mass of the compound. This is the correct answer, as stated in option 'B'.

Atomic Mass:


Before understanding the molecular mass, it is important to understand atomic mass. Atomic mass is the mass of an atom, which is measured in atomic mass units (amu). It is determined by the sum of the protons and neutrons in the atom's nucleus. The atomic mass is listed on the periodic table for each element.

Molecular Mass:


The molecular mass of a compound is the sum of the atomic masses of all atoms present in one molecule of the compound. It is also known as the molecular weight or formula mass. The molecular mass is calculated by adding up the atomic masses of all the atoms in the compound according to the molecular formula.

Example:


Let's take the example of water (H2O). The molecular mass of water is the sum of the atomic masses of two hydrogen atoms and one oxygen atom.
- Atomic mass of hydrogen (H) = 1.00784 amu
- Atomic mass of oxygen (O) = 15.999 amu

The molecular mass of water is calculated as follows:
(2 * atomic mass of hydrogen) + (1 * atomic mass of oxygen)
= (2 * 1.00784 amu) + (1 * 15.999 amu)
= 2.01568 amu + 15.999 amu
= 18.01568 amu

Therefore, the molecular mass of water is approximately 18.01568 amu.

Conclusion:


In conclusion, the sum of the atomic mass of all atoms present in one molecule of a molecular compound is referred to as the molecular mass of the compound. This is the correct answer as stated in option 'B'.