d) Why is methane tetrahedral in shape?

Methane is tetrahedral in shape due to the arrangement of its atoms and the electron clouds around them. Here's a step-by-step explanation:

1. Methane (CH4) consists of one carbon atom and four hydrogen atoms.

2. The carbon atom in the center has four valence electrons, and each hydrogen atom has one valence electron.

3. Carbon forms covalent bonds with each of the four hydrogen atoms, sharing its valence electrons to fill its outer shell and achieve a stable electron configuration.

4. The repulsion between these electron pairs pushes them as far apart as possible, which results in a tetrahedral shape.

5. This shape also minimizes the energy of the molecule, making it the most stable configuration.

6. The bond angles in a tetrahedral molecule are approximately 109.5 degrees, which is the angle formed when the electron pairs are as far apart as possible in three dimensions.

So, the tetrahedral shape of methane is a result of the carbon atom forming four bonds with hydrogen atoms, and the repulsion between these bonds pushing them as far apart as possible.