Question

1. the molecule that has a molecular shape of trigonal pyramidal is _ i because _ ii the statement above is best completed by the answers in row: row i ii □ ph₃ the central atom has a lone pair □ bh₃ the central atom has a lone pair □ ph₃ the central atom has no lone pairs □ bh₃ the central atom has no lone pairs

Explanation:

Step1: Analyze the structure of $PH_3$

Phosphorus ($P$) in $PH_3$ has 5 valence - electrons. It forms 3 bonds with hydrogen atoms, and there is 1 lone - pair of electrons on the central $P$ atom. According to VSEPR (Valence - Shell Electron - Pair Repulsion) theory, the electron - pair geometry around the central atom is tetrahedral, and the molecular geometry is trigonal pyramidal due to the presence of the lone pair.

Step2: Analyze the structure of $BH_3$

Boron ($B$) in $BH_3$ has 3 valence - electrons. It forms 3 bonds with hydrogen atoms and has no lone pairs on the central $B$ atom. According to VSEPR theory, the electron - pair geometry and molecular geometry of $BH_3$ are trigonal planar.

Answer:

$PH_3$, the central atom has a lone pair