 So let's try this one. This one is essentially a NMR problem, but we've also got a mass spec and IR alongside with it. So it says here that the mass spec, the M plus peak at MZ equals 73. Can you tell us anything about that? That's 73. So it's the parent on R, right? So what is the being of? What does that tell us? That's a nitrogen, right? Okay. So it has a nitrogen. So that's one thing we want to remember, okay? Nitrogen's 14, so we can take that away from there and we can figure out how many carbons it has from there, right? So how many carbons do you think this thing has? Four, right? Because if we take 4 times 12, right, that's going to give us 48, then we add 14, and then we'll just have enough room for the hydrogen, right? So it's going to be C4 and what's the H? It's going to be actually a whole lot. And you can tell that when we look here, right? So we have 6 hydrogens, 4 hydrogens, 100. So that adds up to 11. So what is this telling us here? This is 3350. It's not the CN bond, but it's the NH bond. And it's telling us that it's only a single band. So what does that tell us? One hydrogen there, right? In other words, it's a secondary amine, right? Isn't that what you mean to say? Okay, it's a secondary amine. So which one of these three peaks on the NMR is this hydrogen corresponding to? This first one, the second one, or the third? The first one, why would you guess that? Because there's only one H, right? Okay, so that's good. In fact, let's go ahead and kind of draw what the NMR looks like. So we can kind of see it, right? So what do we got? 1.0? So we'll say that's like 1.0. So 1.05, that's somewhere around there, right? We're going to see something that looks like that. And then at 1.15, we'll have a triplet of something that looks like that, okay? And then at 2, we'll say 2.65, so somewhere around there we're going to have a quartet that looks like that, okay? So this says one hydrogen there, six hydrogens there, and four hydrogens there. Okay, so that one hydrogen passed the correspond to that. What is this saying if we've got a triplet? What does that tell us? A triplet? That there's two neighboring hydrogens, okay? But this says four, right? What does that mean? That's not two. Two groups are equivalent, right? And that gives you a clue here, right? So those six hydrogens, there's two methyl groups that are equivalent to each other, okay? So effectively, if this was three and this was two, we made a triplet and a quartet, what would we expect that to look like? An ethyl group, right? So if those two are equivalent, what does this thing look like? It's symmetrical, it's got two ethyl groups on it, okay? That's the model for that, okay? So this is called di-ethylene. Are there any questions on how to do that one? Questions? Are we still recording? Okay, pretty straightforward. This one was really nice because it gave us a lot of things to remind ourselves, you know? If we have the odd, remember there's the nitrogen in it. At 3350, right? We're even going to have a single or double van. The weak tells us that it's the NH bond as opposed to like the OH bond, which would be very strong, okay? But a single van that's telling us that it's a secondary thing as opposed to a primary, okay? Because if it was two vans, then we'd have a primary thing. And then of course, going through the analysis here, you can see that the six to four that those two groups are equivalent, okay? Are there any questions now on this? I think I went over everything about it twice. Okay, good job.