Question

Which of the following will be stable?

• A.
• B.
• C.
• D.

Answer 1

Answer: (B), (C)

The correct options are
B

C

Generally, for checking the stability of a compound, we have to check for the stability of each constituent atom.

We know that,

$\to$ Carbon can make four covalent bonds for stability

$\to$ Bromine can make one

$\to$ Hydrogen can make one

$\to$ Nitrogen can make three.

Now, let's check each option one by one.

If we look at C(3), it is making only 3 covalent bonds.

But we know carbon makes 4 covalent bonds. Therefore, it will not be stable.

This compound will be stable because all carbons make 4 covalent bonds and Nitrogen makes 3 covalent bonds.

This compound will also be stable because all carbons make 4 covalent bonds.

In this compound, if we look at C(1) and C(4), carbon is only making three covalent bonds.

Therefore , it will not be stable. If we only take the molecular formula $-C_4{H}_8$ , there can be stable structures like cyclobutane. But since, the structural formula has clearly depicted that the first and the last carbon atoms have only 3 covalent bonds, this structure is not stable