translation
A translation, a reflection and a rotation
No its not
It will be as you term it 'horizontal stretch' in which the figure is enlarged or reduced in size.
Yes, due to the definition of congruent figures.
Translation, rotation, reflection.
A dilation would produce a similar figure.
only if the mirror is flat
Figures are congruent if and only if they are related by a translation, reflection, or rotation, or some combination of these transformations.
The identity transformation.
No, a figure and its reflection image are congruent. It is like our reflections in a mirror. Hope I answered your question!
A dilation (or scaling) is a transformation that does not always result in an image that is congruent to the original figure. While translations, rotations, and reflections always produce congruent figures, dilations change the size of the figure, which means the image may be similar to, but not congruent with, the original figure.