Hurry! during early research in nuclear energy, why were scientists surprised that the products from splitting a uranium nucleus had less mass than the reactants? 1.they expected that the large release of energy would cause an increase in mass. 2.up to that time, only chemical changes were known to form less mass than they started with. 3.all known changes always started and ended with the same amount of mass. 4.other known nuclear changes resulted in the same mass of products as reactants.

i think it is the 3rd one

3. All known changes always started and ended with the same amount of mass.

Explanation:

From the law of conservation of mass, all the changes started and ended with same amount of mass. The mass could not be formed or destroyed.

Later on it was found that mass could convert to energy and vice-versa via relation:

E = m c² ( Einstein's mass-energy relation)

Thus, early research in nuclear energy brought surprise. The lack of mass in the products was actually converted to an equivalent amount of energy.

answer: a. same unit

explanation: