Final Answer:
The molecular geometry of the underlined carbon atom in the compound CH₂:CHNCH₃ is (a) Tetrahedral. Therefore the correct option is a). Tetrahedral.
Step-by-step explanation:
The molecular geometry is determined by the arrangement of atoms around a central atom, considering both bonding and non-bonding electron pairs. In this compound, the underlined carbon atom is bonded to three other atoms (two hydrogens and one nitrogen) and has no lone pairs of electrons. This arrangement results in a tetrahedral molecular geometry.
A tetrahedral geometry means that the carbon atom is at the center of a tetrahedron, with bond angles of approximately 109.5 degrees between the three hydrogen atoms and the nitrogen atom bonded to it. The tetrahedral geometry is a consequence of the four electron pairs surrounding the central carbon atom, creating a symmetrical and stable spatial arrangement.
Understanding molecular geometry is crucial in predicting the physical and chemical properties of a molecule, as it influences factors such as bond angles and molecular polarity. In this case, the tetrahedral geometry around the underlined carbon atom contributes to the overall shape and reactivity of the CH₂:CHNCH₃ molecule. Therefore the correct option is a). Tetrahedral.