Which calculation correctly gives the molecular mass of nitric acid (HNO₃)?

The correct answer is 1 + 14 + 48.

To find the molecular mass of nitric acid (${HNO}_3$), we calculate the sum of the atomic masses of all the individual atoms present in one molecule of the compound.

Step 1: Identify the constituent elements and the number of atoms of each element:

• Hydrogen (H): 1 atom
• Nitrogen (N): 1 atom
• Oxygen (O): 3 atoms

Step 2: Note the standard approximate atomic masses for each element:

• Atomic mass of Hydrogen (H) = 1 u
• Atomic mass of Nitrogen (N) = 14 u
• Atomic mass of Oxygen (O) = 16 u

Step 3: Calculate the total mass contributed by each element:

• Mass from Hydrogen = 1 × 1 = 1
• Mass from Nitrogen = 1 × 14 = 14
• Mass from Oxygen = 3 × 16 = 48

Step 4: Combine the individual mass contributions:

Molecular mass of ${HNO}_3$ = (Mass of H) + (Mass of N) + (Mass of 3 O atoms)

$\text{Molecular mass}=1+14+48$

Therefore, the calculation that correctly gives the molecular mass of nitric acid is 1 + 14 + 48.