What is the total number of structural isomers of molecular formula C4H9Br.A 3 B 5 C 4 D 6

The molecular formula C4H9Br represents a bromoalkane. To find the total number of structural isomers, we need to consider all the possible ways the carbon atoms can be arranged and where the bromine atom can be placed.

1. The first isomer is 1-bromobutane. This is a straight chain of four carbon atoms, with the bromine atom attached to the first carbon atom.

2. The second isomer is 2-bromobutane. This is also a straight chain of four carbon atoms, but this time the bromine atom is attached to the second carbon atom.

3. The third isomer is 1-bromo-2-methylpropane. This time, the carbon atoms are arranged in a branched chain, with three carbon atoms in the longest chain and one methyl group branching off. The bromine atom is attached to the first carbon atom in the longest chain.

4. The fourth isomer is 2-bromo-2-methylpropane. This is the same as the previous isomer, but the bromine atom is attached to the second carbon atom in the longest chain.

So, the total number of structural isomers of the molecular formula C4H9Br is 4. Therefore, the answer is C.