the number of all possible products excluding stereoisomers obtained on chlorination of n-butane and isobutane are respectively
Well obviously you dont directly want the answer but the method to solve it if not so directly go to the pic.
The trick is to locate different hydrogens . Each one will produce a different mono chloro derivative .
Firstly there's a 3° hydrogen then there's a 2° H and then there are 3 methyl groups all having 1°H but the surprise is all the 3 methyl groups are not the same because two of them are bonded to 3° carbon while the other one is bonded to a 2° carbon .
Replace these H atoms by Cl check the stereochemistry of the compound and you have your answer.