Final answer:
The VSEPR theory predicts the shapes of molecules by considering electron pairs repelling each other. Ammonia and Carbon Tetraiodide have a tetrahedral shape, while Silane has a tetrahedral shape. Hydrogen Selenide has a bent shape.
Step-by-step explanation:
The VSEPR theory is used to predict the shape of molecules by considering electron pairs located in bonds and lone pairs repelling each other and adopting a geometry that places the pairs as far apart as possible. Using this theory, we can predict the shapes of the given molecules:
a) Ammonia (NH₃) has a **pyramidal** shape, with the nitrogen atom at the vertex and the three hydrogen atoms forming the base of the pyramid.
b) Silane (SiH₄) has a **tetrahedral** shape, with the silicon atom at the center and the four hydrogen atoms forming a tetrahedron around it.
c) Hydrogen Selenide (H₂Se) has a **bent** shape, with the two hydrogen atoms at one end and the selenium atom at the other, causing a bent molecular structure.
d) Carbon Tetraiodide (CI₄) has a **tetrahedral** shape, with the carbon atom at the center and the four iodine atoms forming a tetrahedron around it.