Deuterium is represented by

Options

A. `H_1^1`
B. `He_2^2`
C. `H_2^1`
D. `H_3^1`

Answer

To represent deuterium, we need to understand its composition and how isotopes are denoted in chemistry.

### Step-by-Step Solution:

1. **Identify Deuterium**:
- Deuterium is an isotope of hydrogen. This means it has the same atomic number as hydrogen but a different mass number due to the presence of an additional neutron.

2. **Determine Composition**:
- Deuterium consists of:
- 1 proton (which gives it the atomic number of hydrogen, Z = 1)
- 1 neutron
- 1 electron (as it is neutral)

3. **Calculate Mass Number**:
- The mass number (A) is calculated by adding the number of protons and neutrons.
- For deuterium:
- Mass number (A) = Number of protons + Number of neutrons = 1 + 1 = 2

4. **Write the Representation**:
- The standard notation for isotopes is written as:
\[ \text{Element Symbol} \, _Z^A \]
- For deuterium, the element symbol is "H" (for hydrogen), the atomic number (Z) is 1, and the mass number (A) is 2.
- Therefore, deuterium is represented as:
\[ \text{D} \, \text{or} \, \text{H}_1^2 \]

5. **Final Representation**:
- The correct representation of deuterium is:
\[ \text{H}_2^1 \text{ or simply } D \]