Question

which of the following is the correct lewis dot structure for a molecule with the formula hscn? h - s - c≡n h - s - c≡n : h - s - c≡n : h - s - c≡n : question 19 1 pts what is the electron pair geometry for the pbr₃ molecule? trigonal planar tetrahedral trigonal pyramidal bent linear

Explanation:

Step1: Determine Lewis - dot structure of HSCN

Carbon has 4 valence electrons, hydrogen has 1, sulfur has 6 and nitrogen has 5. In HSCN, carbon forms a single - bond with sulfur and a triple - bond with nitrogen to satisfy the octet rule for all atoms. The correct Lewis - dot structure has two lone pairs on sulfur and one lone pair on nitrogen. So the correct Lewis - dot structure of HSCN is $H - \ddot{S}-C\equiv N$.

Step2: Determine electron - pair geometry of $PBr_3$

Phosphorus in $PBr_3$ has 5 valence electrons. It forms 3 single bonds with bromine atoms and has 1 lone pair of electrons. According to the VSEPR (Valence - Shell Electron - Pair Repulsion) theory, the total number of electron pairs (bonding + non - bonding) around the central atom (P) is 4. When the number of electron pairs around the central atom is 4, the electron - pair geometry is tetrahedral.

Answer:

First question: $H - \ddot{S}-C\equiv N$
Second question: tetrahedral