Question

Total number of protons in 36 ml of water at 4°C (density of water is 1 gm/ml)

• A. 20
• B. 16
• C. 20 N$_{A}$
• D. 16 N$_{A}$

Answer 1

Answer: (C)

20 N$_{A}$

Answer 2

1. Calculate the mass of water:

   Given volume of water = 36 ml Given density of water = 1 gm/ml Mass of water = Volume × Density = 36 ml × 1 gm/ml = 36 gm

2. Calculate the molar mass of water (H₂O):

   Atomic mass of H = 1 g/mol Atomic mass of O = 16 g/mol Molar mass of H₂O = (2 × 1) + 16 = 18 g/mol

3. Calculate the number of moles of water:

   Number of moles = Mass / Molar mass = 36 gm / 18 g/mol = 2 moles

4. Calculate the number of water molecules:

   One mole of any substance contains Avogadro's number (N$_{A}$) of molecules. Number of water molecules = Number of moles × N$_{A}$ = 2 × N$_{A}$ molecules

5. Determine the number of protons in one water molecule (H₂O):

   Hydrogen (H) has 1 proton (atomic number = 1). Oxygen (O) has 8 protons (atomic number = 8). Number of protons in one H₂O molecule = (2 × protons in H) + (protons in O) = (2 × 1) + 8 = 2 + 8 = 10 protons

6. Calculate the total number of protons:

   Total number of protons = Number of water molecules × Protons per molecule = (2 N$_{A}$) × 10 = 20 N$_{A}$

The total number of protons in 36 ml of water is 20 N$_{A}$.