Here's why:

* Ionic Compound: Ammonium fluoride is an ionic compound, meaning it's formed by the attraction between a positively charged ammonium ion (NH₄⁺) and a negatively charged fluoride ion (F⁻).

* Polar Solvent: Water is a polar solvent, meaning it has a partial positive charge on one end (hydrogen) and a partial negative charge on the other (oxygen).

* Dissolution: When ammonium fluoride is added to water, the polar water molecules surround the ions, breaking the ionic bonds and pulling them apart. This process is called dissolution, and it results in a homogeneous mixture of ammonium and fluoride ions dissolved in water.

Note: The solubility of ammonium fluoride is quite high. It is readily soluble in water at room temperature.