Manhattan Project Trivia
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50 free Manhattan Project trivia questions with answers — history quiz, new questions added Aug 2026.
This Manhattan Project trivia quiz covers the wartime programme that built the first atomic bombs, from the 1939 letter Leo Szilard drafted for Einstein to the handover to the Atomic Energy Commission in 1947. It starts with the origins: Hahn and Strassmann's discovery of fission, the Frisch-Peierls memorandum and MAUD report, the Australian physicist who found the British findings locked in a safe, and Roosevelt's decision to give the job to the Army. It then explains how the project got its name, why Leslie Groves was promoted before he took charge, and why a scientist with no Nobel Prize was chosen to run Los Alamos. The middle of the quiz visits the sites and the science: the squash court under Stagg Field, the calutrons of Y-12 and the 14,700 tons of Treasury silver in their magnets, the half-mile-long K-25 building, the reactors at Hanford, the ranch school in New Mexico, the difference between Little Boy and Fat Man, and the Trinity test with its cover story about an ammunition dump. It finishes with the 509th Composite Group, Enola Gay and Bockscar, the clouds over Kokura, the third bomb Truman stopped, Klaus Fuchs and the other spies, Operation Alsos and Farm Hall, and the final bill of about two billion dollars. Questions range from easy to expert. Every answer was checked against the Wikipedia article on the Manhattan Project.
30 of 50 questions with answers and explanations. Play the quiz
Q 01Which Army general directed the Manhattan Project from 1942 to 1946?
Leslie Groves
He was promoted to brigadier general before taking over because it was felt the title would carry more weight with the scientists.
Q 02Who was the director of the Los Alamos Laboratory that designed the bombs?
J. Robert Oppenheimer
Compton recommended him even though he had no Nobel Prize, little administrative experience and communist associates.
Q 03The project took its name from what?
The location of the Army's first headquarters
Colonel Marshall's temporary HQ was at 270 Broadway, and engineer districts were named for their cities; the earlier codename was 'Development of Substitute Materials'.
Q 04What was the code name of the British atomic bomb programme that the Manhattan Project absorbed?
Tube Alloys
The MAUD Committee's 1941 report had convinced the Americans a bomb was feasible; the Quebec Agreement later formalised cooperation.
Q 05Roughly how many people did the Manhattan Project employ at its peak?
About 130,000
In June 1944 that included 84,500 construction workers, 40,500 plant operators and 1,800 military personnel.
Q 06Which two physicists drafted the August 1939 letter Einstein signed and sent to Roosevelt?
Leo Szilard and Eugene Wigner
It warned of 'extremely powerful bombs of a new type' and urged America to stockpile uranium ore.
Q 07Which two German chemists discovered nuclear fission in 1938?
Otto Hahn and Fritz Strassmann
Lise Meitner and Otto Frisch supplied the theoretical explanation, and fear of a German bomb drove the American effort.
Q 08Which Australian physicist found in 1941 that Lyman Briggs had locked the MAUD report in a safe?
Mark Oliphant
He persuaded Ernest Lawrence at Berkeley, who in turn alerted Conant and Compton, and the American programme accelerated.
Q 09Why did Roosevelt hand the atomic project to the service he chose rather than the Navy?
It had more experience managing large-scale construction
He approved acceleration on 9 October 1941 and set up a Top Policy Group whose meetings he never attended.
Q 10On what date did Fermi's team achieve the first self-sustaining nuclear chain reaction?
2 December 1942
Compton phoned Conant in code: 'The Italian navigator has just landed in the new world.'
Q 11Where was Fermi's first reactor pile built after delays at the planned forest site?
Under the bleachers of Stagg Field
Delays at the planned Argonne 'Site A' forced the move on campus; the pile was dismantled and rebuilt in the forest in 1943.
Q 12What term did Fermi coin for the early prototype nuclear reactors built at Columbia?
Atomic piles
The Navy had given Columbia $6,000 in 1940, most of it spent by Fermi and Szilard on graphite.
Q 13What was the official name of the uranium-enrichment site at Oak Ridge, Tennessee?
Clinton Engineer Works
Q 21Which institution operated the Los Alamos laboratory under contract to the War Department?
The University of California
Robert Bacher and Isidor Rabi had balked at the idea of scientists being commissioned into the Army, so a compromise was found.
Q 22Who ran the Santa Fe branch office where new Los Alamos arrivals were met and issued passes?
Dorothy McKibbin
Los Alamos was known as 'Site Y' or 'the Hill' during the war.
Q 23Which two bomb designs did Los Alamos produce for use in the war?
Little Boy and Fat Man
Fat Man was a fallback until 1944, when Hanford plutonium proved too rich in plutonium-240 for a gun-type bomb.
About 1,000 families were displaced from 56,000 acres bought by eminent domain for $3.5 million.
Q 14In which state was the Hanford Engineer Works, site of the first industrial-scale plutonium reactors?
Washington
DuPont wanted the site far from Oak Ridge after worries that Knoxville was too close in case of accident.
Q 15What did the name 'calutron', the electromagnetic separation device, derive from?
California, university and cyclotron
The process was inelegant and inefficient but proven; it was housed at the Y-12 plant at Oak Ridge.
Q 16What did the project borrow from the US Treasury to wind the calutron magnets, because copper was scarce?
14,700 tons of silver
The 1,000-troy-ounce bars from West Point were cast into billets and extruded into strips; silver replaced copper at an 11:10 ratio.
Q 17How long was the U-shaped K-25 gaseous diffusion building at Oak Ridge?
Half a mile
The four-storey structure held 54 contiguous buildings; production started in February 1945.
Q 18What was the code name of the plutonium plant designated S-50 designed to do?
Thermal diffusion of uranium
By March 1945 all three enrichment methods, S-50, K-25 and Y-12, were run in series, each feeding the next.
Q 19What percentage of natural uranium is the fissile isotope uranium-235?
0.7%
The rest is uranium-238, so the isotopes had to be physically separated by electromagnetic, gaseous or thermal means.
Q 20What occupied the New Mexico mesa Oppenheimer chose as the site of the bomb laboratory?
A boys' ranch school
Oppenheimer owned a ranch near Albuquerque; the lab was known during the war as 'Site Y' or 'the Hill'.
Q 24Why was the gun-type design abandoned for the Hanford-fuelled bomb in 1944?
The fuel contained too much of the isotope Pu-240
That forced the switch to the complex implosion design with explosive lenses, and made a full-scale test necessary.
Q 25What was the code name Oppenheimer gave the first nuclear test?
Trinity
Kenneth Bainbridge chose the Alamogordo Bombing Range, and the device itself was nicknamed 'the gadget'.
Q 26On what date and at what time did the first nuclear device explode?
05:30 on 16 July 1945
It yielded around 20 kilotons, left a 250-foot crater of trinitite glass and was heard as far away as El Paso.
Q 27What cover story did Groves issue to explain the first test blast?
An ammunition dump explosion at Alamogordo Field
The shock wave was felt over 100 miles away and the mushroom cloud rose 7.5 miles.
Q 28What was 'Jumbo' at the Alamogordo site?
A 214-ton steel vessel to recover plutonium in a fizzle
Confidence in implosion grew so high it was never used; it was stood on a tower 800 yards away and survived the blast.
Q 29From which Hindu scripture did Oppenheimer recall 'Now I am become Death, destroyer of worlds' at the Trinity test?
The Bhagavad Gita
He cited verses XI,12 and XI,32; the gadget had been winched up a 100-foot tower two days earlier.
Q 30What was the code name for the modification of B-29 bombers to carry atomic bombs?
Silverplate
The British Avro Lancaster was the only Allied plane that could carry the bombs unmodified, but a British aircraft was politically awkward.