USA HISTORY

Detailed explanation-1: -About 64 kilograms of highly-enriched uranium was used in the bomb which had a 16 kiloton yield (i.e. it was equivalent to 16, 000 tonnes of TNT). It was released over Hiroshima, Japan’s seventh largest city, on 6 August 1945. Some 90% of the city was destroyed.

Detailed explanation-2: -Nuclear weapons typically use a concentration of more than 90 percent uranium-235. 15 kilograms: weight of a solid sphere of 100 percent uranium-235 just large enough to achieve a critical mass with a beryllium reflector.