10 most difficult USA riddles A list of ten (out of 51) USA related questions that are the most often answered incorrectly USA quiz When did the USA introduce metric system as preferred for weights and measures?1975. President Gerald Ford signed the Metric Conversion Act in1975. It declared the metric system "the preferred system of weights and measures for United States trade and commerce", but permitted the use of United States customary units in all activities. The metrification board was abolished in 1982 by President Ronald Reagan.very hard 17% nevernever62%180518054%1866186615%1975197517%Created by: Ninjai. Statistics based on 289 answers in 3 languages »measures riddles » What is weapon shown on the image?Mark 4 Carbine. In 1990's U.S. army and marines replaced M16 Rifles with newly designed M4 Carbines which were more compact and comfortable in use.By 2015 M4 was made prime infantry rifle in U.S. weaponry.very hard 18% AK-sAK-s18%Mark 4 CarbineMark 4 Carbine18%M16 RifleM16 Rifle63%Ump-45Ump-450%Created by: grifi bastion. Statistics based on 11 answers »20th century riddles » Telstar was the first, non-military satellite launched in 1962. It broke merely after 5 months. What was the cause?Nuclear explosion. In July 1962 USA conducted high altitude nuclear test of antirocket of 1.4 megatonnes of TNT. The explosion conducted at the height of 250 miles destroyed 1/3 of all satellites, including Telstar.very hard 18% magnetic stormmagnetic storm20%collision with meteorcollision with meteor23%nuclear explosionnuclear explosion18%software flawsoftware flaw37%Created by: smyru. Statistics based on 482 answers in 2 languages »nuclear tests riddles » Which of these fast food chains is the oldest?KFC-1930. McDonald's-1940. Dunkin 'Donuts-1950 Burger King-1954very hard 25% KFCKFC25%McDonald'sMcDonald's25%Dunkin’ DonutsDunkin’ Donuts33%Burger KingBurger King15%Created by: Tschuka . Statistics based on 1472 answers in 3 languages »brands riddles » Which team has won the most Super Bowl titles?Pittsburgh Steelers has won this trophy six times in 1974, 1975, 1978, 1979, 2005 and 2008.very hard 26% Dallas CowboysDallas Cowboys21%Pittsburgh SteelersPittsburgh Steelers26%San Francisco 49ersSan Francisco 49ers14%New York GiantsNew York Giants37%Created by: Ninjai. Statistics based on 431 answers in 3 languages »sport riddles » Which country didn't try to colonize California?Portugal. As a matter of fact the first European who explored California was Portuguese on Spanish duty - Cabrillo. However, his country never tried to estabilish colonies there. very hard 27% SpainSpain4%PortugalPortugal27%RussiaRussia54%Great Britain Great Britain 14%Created by: Mikołaj Sołkiewicz. Statistics based on 392 answers in 2 languages »California riddles » How many amendments to the USA constitution have been repealed?One. Of 27 ratified amendments to USA Constitution only one has been repealed. This was 18th amendment of 1917 that had introduced the American prohibition. It was repealed in 1933. very hard 28% oneone28%threethree22%sixsix13%nonenone34%Created by: smyru. Statistics based on 1156 answers in 2 languages »prohibition riddles » This is a statue of a heroic dog, erected in 1925 in Central Park. What was the dog's name?Balto was a sled dog who led his team on the final leg of the 1925 serum run to Nome, in which diphtheria antitoxin was transported to combat an outbreak of the disease. After the mission's success, Balto and the Norwegian Gunnar Kaasen, who drove the sled, became celebrities.very hard 29% HachikoHachiko38%LaikaLaika20%BaltoBalto29%Rin Tin TinRin Tin Tin12%Created by: Tschuka . Statistics based on 1296 answers in 2 languages »Alaska riddles » What is the highest face value of the US dollar?100 000. It is a banknote that does not exist in general circulation. There is a portrait of Woodrow Wilson - the 28th President of the United States who held this office in 1913-1921.very hard 31% 1 0001 00037%5 0005 00016%10 00010 00014%100 000100 00031%Created by: Tschuka . Statistics based on 681 answers in 2 languages »currencies riddles » Which of these cities has the closest latitude to Washington, D.C.?Beijing. Washington, D.C. - 38° 54′ 17″ N, Beijing - 39° 55′ 0″ N, Tbilisi - 41° 43′ 0″ N, Rome - 41° 54′ 0″ N and Tokyo - 35° 41′ 0″ N.very hard 31% RomeRome34%TbilisiTbilisi13%BeijingBeijing31%TokyoTokyo19%Created by: Ninjai. Statistics based on 263 answers in 2 languages »maps riddles » Play USA quiz and see all the questions.