Hi Ijaz,

CD4051 is a multiplexer/de-multiplexer.
Here is the data sheet link : http://www-s.ti.com/sc/psheet...hs047e.pdf.

Now if using RTD also need to consider for lead wire resistance and for that need to use atleast two CD4051, one to select any one of the RTD analog signal at any given time and and another for to supply referance voltage to that particular RTD.

This is very cheap and reliable solution and what I did the same in my design.

Have fun,

Ramesh