Question: What was the capital of the union of provinces in the Río de la Plata comprised by most of the former dependencies from the last to be organized and also the shortest-lived of the Viceroyalties of the Spanish Empire in the Americas?
Sentence (from "Viceroyalty of the Río de la Plata"): The Viceroyalty of the Río de la Plata (Spanish: "Virreinato del Río de la Plata" ) was the last to be organized and also the shortest-lived of the Viceroyalties of the Spanish Empire in the Americas.
Relevant evidence: Yes