What was the fissionable material used in the bombs dropped at Nagasaki (Japan) in the year 1945?

Correct answer: (c) Plutonium

Explanation

The Nagasaki bomb ("Fat Man", 1945) used Plutonium (Pu, atomic number 94) as its fissionable material.

The earlier Hiroshima bomb used Uranium, which is why uranium is a tempting distractor.

Sodium and potassium are reactive metals, not fissionable nuclear fuels.