Question

1. when its electron dot diagram is drawn, which molecule below appears to be an exception to the stable octet rule?

co₂
bh₃
nh₃
ph₃

Explanation:

The stable - octet rule states that atoms tend to gain, lose, or share electrons to have eight electrons in their outer shell. In $CO_2$, carbon shares electrons with oxygen to complete its octet and oxygen also has an octet. In $NH_3$, nitrogen shares electrons with hydrogen and has a full - octet (including lone pairs), and in $PH_3$, phosphorus shares electrons with hydrogen and has an octet. However, in $BH_3$, boron has only 6 electrons in its outer shell after sharing with hydrogen atoms, which is an exception to the octet rule.

Answer:

BH₃