Question

Refer to the octet rule to decipher which of the following is an exception (carbon dioxide, phosphorous triflouride, arsenic pentaflouride, ammonia, or water) and which of the following is also an exception (boron trichlouride, borohydride, and borazine.

Answer 1

`\begin{gathered} (i_)\text{ Arsenic Pentafluoride} \\ (ii)\text{ Borohydride} \end{gathered}`

Step-by-step explanation:

a) Here, we want to get the molecule that does not obey the octet rule

The correct choice here is arsenic pentafluoride.

Arsenic has 5 valence electrons, then it takes in one each from each of the fluorine atoms. This brings a total of 10 which is more than the 8 stipulated in the octet rule.

The octet rule states that the central atom should have a maximum of 8 electrons

b) Here, we want to get an exception to the octet rule

The correct answer choice here is borohydride. Borohydride has a total of 10 electrons (5 from Boron, 4 from hydrogen (1 from each) and an extra 1)) does not follow or obey the octet rule