To determine which molecule has a stable configuration, we should look for the one that satisfies the octet rule (for most elements), meaning that each atom will have a full outer shell of electrons. A stable molecule typically involves elements that achieve a noble gas configuration.
Let's analyze the options:
A. PH4 - Phosphorus typically can have more than four bonds, but in this configuration, it's unlikely to have a stable arrangement, and it doesn’t provide a full octet for all atoms involved.
B. CaBr2 - This is an ionic compound where calcium (Ca) donates two electrons to two bromine (Br) atoms. Calcium achieves a stable octet by losing its two valence electrons, and each bromine achieves a stable octet by gaining one electron. This compound is stable.
C. SiO5 - Silicon typically forms four bonds, and having five oxygen atoms bonded to silicon is unlikely to create a stable structure. This configuration is not common for silicon.
D. NaCl2 - Sodium (Na) typically forms one bond and would not feasibly bond with two chlorine (Cl) atoms to create a stable or common compound. Therefore, it does not produce a stable configuration.
Based on this analysis, the most suitable answer is B. CaBr2, as it involves the stabilization through ionic bonding, achieving a full outer shell of electrons for both calcium and bromine atoms.