There are 5 positional isomers for C3H5Cl3.

Explanation:

Positional isomers are the compounds that have the same molecular formula but differ in the position of atoms or functional groups within the molecule. For C3H5Cl3, the possible structural isomers are:

1. 1,1,1-Trichloropropane
In this isomer, all the three chlorine atoms are attached to the first carbon atom of the propane chain.

2. 1,1,2-Trichloropropane
In this isomer, two chlorine atoms are attached to the first carbon atom and one chlorine atom is attached to the second carbon atom of the propane chain.

3. 1,2,2-Trichloropropane
In this isomer, two chlorine atoms are attached to the second carbon atom and one chlorine atom is attached to the first carbon atom of the propane chain.

4. 1,2,3-Trichloropropane
In this isomer, one chlorine atom is attached to each of the three carbon atoms of the propane chain.

5. 2,2,2-Trichloropropane
In this isomer, all the three chlorine atoms are attached to the second carbon atom of the propane chain.

Therefore, there are 5 positional isomers for C3H5Cl3.