The activation energy of a chemical reaction can be decreased by the addition of
(1) a catalyst (3) electrical energy
(2) an indicator (4) thermal energy

The correct answer is option 1. It should be noted that a catalyst does not lower or decrease the activation energy because instead it provides an alternative route for the reaction to proceed. This speeds up a chemical reaction without being changed. 

It could possibly be beneficial if the experiment is successful.

Aquantity of that isotope to decay to 1/2 of  its original value