What does the word contribution mean?

When curium-242 is bombarded with an alpha particle, two products are formed, one of which is a nudge on. what is the other product

650.j is the same amount of energy as? 2720cal1550cal650.cal2.72cal

Which statement about hf is true? it is zero for any compound in its standard state. it is positive when the bonds of the product store more energy than those of the reactants. it is negative when a compound forms from elements in their standard states. it is zero for any element that is in the liquid state.