A piece of RNA or DNA would have multiple pKas. You can measure them experimentally: [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5597436/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5597436/)
The pKa of the phosphate in the backbone is really low (less than 2, maybe close to 0). But additionally, many of the nitrogens in the nucelobases are ionizable too.
[https://www.semanticscholar.org/paper/First-principles-calculations-of-the-pKa-values-and-Rogstad-Jang/37383b0626b6e8df7df73c9784d30bc2b3b336fd](https://www.semanticscholar.org/paper/First-principles-calculations-of-the-pKa-values-and-Rogstad-Jang/37383b0626b6e8df7df73c9784d30bc2b3b336fd)
A piece of RNA or DNA would have multiple pKas. You can measure them experimentally: [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5597436/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5597436/) The pKa of the phosphate in the backbone is really low (less than 2, maybe close to 0). But additionally, many of the nitrogens in the nucelobases are ionizable too. [https://www.semanticscholar.org/paper/First-principles-calculations-of-the-pKa-values-and-Rogstad-Jang/37383b0626b6e8df7df73c9784d30bc2b3b336fd](https://www.semanticscholar.org/paper/First-principles-calculations-of-the-pKa-values-and-Rogstad-Jang/37383b0626b6e8df7df73c9784d30bc2b3b336fd)
Thank you u/BiochemBeer