Density of heavy water is

Options

A. more than that of ordinary water
B. equal to that of ordinary water
C. less than that of ordinary water
D. none of the above

Explanation

To determine the density of heavy water (D2O) compared to ordinary water (H2O), we can follow these steps:

### Step 1: Understand the Composition of Heavy Water and Ordinary Water
- Ordinary water (H2O) consists of two hydrogen atoms (H) and one oxygen atom (O).
- Heavy water (D2O) consists of two deuterium atoms (D) and one oxygen atom (O). Deuterium is an isotope of hydrogen that contains one neutron and one proton.

### Step 2: Compare the Atomic Masses
- The atomic mass of hydrogen (H) is approximately 1 u (atomic mass unit).
- The atomic mass of deuterium (D) is approximately 2 u (1 proton + 1 neutron).
- Therefore, the molecular mass of ordinary water (H2O) is:
\[ 2 \times 1 \, \text{u (for H)} + 16 \, \text{u (for O)} = 18 \, \text{u} \]
- The molecular mass of heavy water (D2O) is:
\[ 2 \times 2 \, \text{u (for D)} + 16 \, \text{u (for O)} = 20 \, \text{u} \]

### Step 3: Understand the Implications of Molecular Mass on Density
- Density is defined as mass per unit volume. Since heavy water has a higher molecular mass (20 u) compared to ordinary water (18 u), it will have a greater density.
- The presence of the additional neutron in deuterium increases the overall mass of the heavy water molecule.

### Step 4: Conclusion
- Since heavy water (D2O) has a greater molecular mass than ordinary water (H2O), it follows that the density of heavy water is greater than that of ordinary water.

### Final Answer
The density of heavy water is more than that of ordinary water.

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