 Now we need a hexagonal acid. And it has a hexagonal acid. Why hexagonal acid? Because we already solved the problem. I don't know what you're thinking. Okay, so a strong acid, so a strong acid. Now, if you have a chemical that is not going to be used, you would realize that we have a strong acid. We can example a strong acid that is a gas cell which gives H plus plus here minus, and V is today, and this is V. And this is V. So, can I take an H? 4 plus plus 4 H minus. Fine? Okay. Now, this is a strong acid in V phase. What then happens? We're going to react with H2O to give... And this is? You should know. No, we're going to react. V, Casanox, so you should be more acid. It started off this class, I told you something. So, K1. H plus. H plus and? K minus. Minus. Are you ready? Yes, sir. Okay, next is? Buffer. No. Oh, you're not taking the brain, sir. K1. I don't know. Casanox on it is?