Task: Question Answering
Input (English): Passage: The final large reception room on the first floor is the Hondecoeter Room (16), so named because of the three huge oil paintings by Melchior d'Hondecoeter (1636–1695), depicting scenes of birds in courtyards, which are fitted into the neo-Carolean panelling. The panelling was introduced to the room by the 3rd Earl Brownlow in 1876, when it was furnished as the principal dining room of the mansion. The room was initially created as a library in 1808 from the upper part of the earlier kitchen which had originally risen two stories. The West staircase (14) was originally a service stairs, and would have been plainer in decor, but by the late nineteenth century it was in regular use by the family.Either side of the Marble Hall, lie the Great Staircase (2) and the Tapestry Room (11), which contains a collection of early eighteenth century Mortlake tapestries. The Great Staircase to the east of the Marble Hall is unusually placed at Belton, as in a house of this period one would expect to find the staircase in the hall. The stairs rise in three flights around the west, north, and east walls to the former Great Dining Room above the Marble Hall. Thus the staircase served as an important state procession link between the three principal reception rooms of the house. The Great Dining Room, now the Library, has been greatly altered and all traces of Carolean decoration removed, first by James Wyatt in 1778 when it was transformed into a drawing room with a vaulted ceiling, and again in 1876, when its use was again changed, this time to a library. The room contains some 6000 volumes, a superb example of book collecting over 350 years. When Lord Tyrconnel died in 1754 a catalogue of his library identified almost 2,300 books. Almost all of these remain in the Belton library today. Rupert Gunnis attributed the carved marble chimneypiece depicting two Roman goddesses to Sir Richard Westmacott.Leading from the Library is the Queen's Room, the former "Best Bed Chamber". This panelled room was redecorated in 1841 for the visit of Queen Adelaide, widow of William IV, when its former function as a state bedroom was resurrected. It contains the great canopied Rococo-style bed in which the Queen slept, complete with the royal monogram "AR" (Adelaide Regina) embroidered on the bedhead. Other rooms on the second floor are mostly bedrooms, which include the Chinese Room (directly above the Tyrconnel Room) with its original hand-painted 18th-century Chinese wallpaper, the Yellow Room (directly above the Blue Room), and the Windsor Bedroom (directly above the School Room), so called following its use by King Edward VIII of the United Kingdom, who became the Duke of Windsor after the abdication crisis of 1936. Edward visited Belton in the 1930s with his mistress Wallis Simpson, and the 6th Baron Brownlow was heavily involved in the crisis thanks to his position as the King's Lord-in-waiting. Today, Belton has a permanent exhibition devoted to that event. Another royal visitor, Charles, Prince of Wales, also used the room frequently while a cadet at nearby RAF Cranwell. 
Question: What was the name of Williams IV's widow?
Output (English): Queen Adelaide.