can i create a selection in spectral view accurately ?

No you can't, I'm afraid. The purpose of having a visual spectral display is that you can manipulate tools around it visually, whilst listening to the results of your manipulation. And the concept of 'accurate' is a bit moot too - what you are looking at with the spectral view is filtering which cannot have steep sides to it, because if it did, it would ring badly.

If you want, for whatever reason, to position a filter accurately using actual numbers, the the tool to use is the Scientific Filter, which is specifically designed to do this.