Can we say that the scrips that carry max weightage in Nifty50 basket are correlated and those in the bottom of the list not correlated?

By correlated if you are asking if Nifty moves up, the stock also moves up and vice versa, you need to look at the beta of the stock and not the weightage. Check this question on what beta means. 

Yes the stocks with high weightage can move nifty up/down, but that is provided all the remaining 49 stocks do nothing.