Hii aspirant..

Although both of these courses seems bit same but they are quite different. 

In BSc Chemistry you will be taught chemistry in detail that is you will be taught physical, organic and inorganic chemistry  in a broad manner. Where as in physical science with chemistry you will be taught three subjects in major that is mathematics, physics and chemistry if you opt for chemistry. 

If you are interested in chemistry and want to study the subject in major then ofcourse Bsc Chemistry is a better option as it will help you to learn Chemistry in detail. But if you want to study other subjects as well with chemistry then BSc physical science is better option.

The only advantage of Bsc physical science is that in your MSc for Masters you can choose any of those three subjects where is in BSc Chemistry you can only choose chemistry for your masters.

So I would recommend you to choose your subject wisely according to your interest.

Hope it helps. 

Best of luck.