extra tax saving through CPF

Hi, I have heard of additional tax excemption for CPF contributions. My tax current savings are the following:
u/s 80 C (LIC+PLI+PPF) = Rs. 42,000
u/s 80 CCD(1) & CCD(2) ie, CPF = 1,10,000
so i am covering the 80 C limit ie, 1.5 Lakh.

Now my question is that if i am depositing further Rs. 50,000 through ELSS, whether i can claim for Rs. 2 lakh saving limit. pl advice.
I also wanted to know what is 80CCD(1b)?