Question

1. When the fission of uranium-235 is carried out, about 0.1 percent of the mass of the reactants is lost during the reaction. What happens to this “lost” mass?

Answer 1

The correct answer to the question is that the lost mass has been converted into energy.

EXPLANATION:

From Einstein's theory, we know that energy and mass are inter convertible .

When some amount of mass is lost, same amount of energy equivalent to mass is produced.

Let us consider m is the mass lost during any reaction. Hence, the amount of energy produced will be-

                                 Energy E = $mc^2$                

Here, c is the velocity of light i.e c = $3\times 10^8\ m/s$

As per the question, uranium-235 undergoes fission. The amount of mass defect is 0.1 %.

The mass defect is defined as the difference between mass of reactants and products. During the fission, energy is produced.

The energy produced in this reaction is nothing else than the energy equivalent to mass defect.  Approximately 199.5 Mev of energy equivalent to this mass defect is produced in this reaction.

Answer 2

It is converted into energy.