Calculate the oxidation number of the underlined atoms in the following species.
`ul(N)H_(2)OH,[ul(Co)(NH_(3))_(5)Cl]Cl_(2),(ul(N_(2))H_(5))_(2)SO_(4),ul(Mg)_(3)N_(2)`

Explanation

To calculate the oxidation numbers of the underlined atoms in the given species, we will follow a systematic approach for each compound.

### Step-by-Step Solution:

1. **For NH₂OH (Hydroxylamine)**:
- Let the oxidation number of nitrogen (N) be \( X \).
- The oxidation numbers of the other atoms are:
- Hydrogen (H) = +1 (there are 3 H atoms)
- Oxygen (O) = -2
- The overall charge of the molecule is 0.
- Therefore, we can set up the equation:
\[ X + 3(+1) + (-2) = 0 \]
\[ X + 3 - 2 = 0 \]
\[ X + 1 = 0 \implies X = -1 \]
- **Oxidation number of N in NH₂OH = -1**.

2. **For [Co(NH₃)₅Cl]Cl₂ (Cobalt complex)**:
- Let the oxidation number of cobalt (Co) be \( X \).
- The oxidation numbers of the other atoms are:
- Ammonia (NH₃) = 0 (neutral ligand)
- Chlorine (Cl) = -1 (there is 1 Cl in the coordination sphere)
- The overall charge of the complex is +2 (since it is balanced by 2 Cl⁻ ions outside).
- Therefore, we can set up the equation:
\[ X + 5(0) + (-1) = +2 \]
\[ X - 1 = +2 \implies X = +3 \]
- **Oxidation number of Co in [Co(NH₃)₅Cl]Cl₂ = +3**.

3. **For (N₂H₅)₂SO₄ (Hydrazine sulfate)**:
- Let the oxidation number of nitrogen (N) be \( X \).
- The oxidation numbers of the other atoms are:
- Hydrogen (H) = +1 (there are 5 H atoms)
- Sulfate (SO₄) = -2 (the sulfate ion has a charge of -2)
- The overall charge of the cation (N₂H₅)²⁺ is +1.
- Therefore, we can set up the equation:
\[ 2X + 5(+1) = +1 \]
\[ 2X + 5 = +1 \implies 2X = 1 - 5 \implies 2X = -4 \implies X = -2 \]
- **Oxidation number of N in (N₂H₅)₂SO₄ = -2**.

4. **For Mg₃N₂ (Magnesium nitride)**:
- Let the oxidation number of magnesium (Mg) be \( X \).
- The oxidation numbers of the other atoms are:
- Nitrogen (N) = -3 (since there are 2 N atoms)
- The overall charge of the compound is 0.
- Therefore, we can set up the equation:
\[ 3X + 2(-3) = 0 \]
\[ 3X - 6 = 0 \implies 3X = 6 \implies X = +2 \]
- **Oxidation number of Mg in Mg₃N₂ = +2**.

### Final Results:
- Oxidation number of N in NH₂OH = -1
- Oxidation number of Co in [Co(NH₃)₅Cl]Cl₂ = +3
- Oxidation number of N in (N₂H₅)₂SO₄ = -2
- Oxidation number of Mg in Mg₃N₂ = +2