Which one of the following statement is true for Ammonium ion?

Options

A. All bonds are ionic
B. All bonds are coordinate covalent
C. H atoms are situated at the comers of a square
D. H atoms are situated at the corners of a tetrahedron

Explanation

To determine which statement is true for the ammonium ion (NH4+), we will analyze each of the given options step by step.

### Step 1: Understand the structure of the ammonium ion (NH4+)
- The ammonium ion consists of one nitrogen atom and four hydrogen atoms.
- It can be formed when ammonia (NH3) reacts with a proton (H+). In this process, nitrogen donates a lone pair of electrons to bond with the proton, resulting in the ammonium ion.

### Step 2: Analyze the bonding in NH4+
- In NH4+, three of the hydrogen atoms are bonded to nitrogen through covalent bonds, where each hydrogen shares one electron with nitrogen.
- The bond between nitrogen and the fourth hydrogen is a coordinate covalent bond, where nitrogen donates both electrons to bond with the hydrogen ion (H+).

### Step 3: Evaluate the statements
1. **All bonds are ionic**: This statement is false. The bonds in NH4+ are primarily covalent, with one being a coordinate covalent bond.

2. **All bonds are coordinate covalent**: This statement is also false. Only one bond is coordinate covalent; the other three are regular covalent bonds.

3. **H atoms are situated at the corners of a square**: This statement is false. The geometry of NH4+ is not square; it is tetrahedral.

4. **H atoms are situated at the corners of a tetrahedron**: This statement is true. The geometry of NH4+ is tetrahedral, with the nitrogen atom at the center and the four hydrogen atoms at the corners of the tetrahedron.

### Conclusion
The correct answer is that the hydrogen atoms in the ammonium ion (NH4+) are situated at the corners of a tetrahedron.

### Final Answer
**The true statement for the ammonium ion is: H atoms are situated at the corners of a tetrahedron.**

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