Helpp!! Please it’s balancing equations and I really need help in it it’s so hard theirs two other parts if you can help with those too:))

What is avogadro’s number, and why is it useful

Ill give brainiestif one neutron initiates a fission event that produces two neutrons in the products, how many new reactions can now be initiated? if each of the neutrons produced in the first fission event then initiates a fission event that produces one neutron in the products, how many new reactions can now be initiated by each neutron? how many neutrons in total were produced by the two fission events described?

In a copper wire, a temperature increase is the result of which of the following