Someone please help me with this !??

Anybody wanna ? (picture included? )

If gases like carbon dioxide and methane make up less than 1% of the total atmosphere, why is it important for scientists to monitor changes in percentages of these gases?

Examine the equation. 23490th→23088ra+42he what kind of barrier would you need to block the radioactive particles from this reaction? a.a piece of paper b.a sheet of aluminum foil c. a two-inch block of lead d. a solid concrete block