Molecular mass is defined as the

Options

A. mass of one atom compared with the mass of one molecule
B. mass of one atom compared with the mass of one atom of hydrogen
C. mass of one molecule of any substance compared with the mass of one atom of C-12
D. none of the above.

Answer

**Step-by-Step Solution:**

1. **Understanding Molecular Mass**:
- Molecular mass is defined as the mass of one molecule of a substance. It represents the total mass of all the atoms that make up a molecule.

2. **Comparison with Carbon-12**:
- To quantify molecular mass, it is often compared to the mass of a specific isotope of carbon, which is carbon-12. The mass of one atom of carbon-12 is defined as 12 atomic mass units (amu).

3. **Calculating Molecular Mass**:
- The molecular mass of a substance can be calculated by adding the atomic masses of all the atoms present in the molecule. For example, for water (H₂O), the molecular mass would be calculated as:
- Hydrogen (H) has an atomic mass of approximately 1 amu, and there are 2 hydrogen atoms.
- Oxygen (O) has an atomic mass of approximately 16 amu, and there is 1 oxygen atom.
- Therefore, the molecular mass of water = (2 × 1) + (1 × 16) = 2 + 16 = 18 amu.

4. **Conclusion**:
- Thus, molecular mass is a crucial concept in chemistry that allows us to understand the mass of substances at the molecular level, and it is expressed in atomic mass units (amu).

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