Yeah...it sounds like a Biochemistry question, which I haven't taken yet. Just using what I know from lower-div sci classes to answer this question. I know that RNA & DNA are structurally different though...RNA is single-stranded and DNA is double-stranded. So, if you take that notion alone (without adding a strand of RNA to another one), you'd realize DNA was a stronger OH bond, thus harder to dissolve or for NaOH to ionize it.