How do i find the reactants for the combustion reaction?

Evaluate this exponential expression,8. (2 + 3)2 – 42

Achange in the number of neutrons in an atom will change an blank . when the number of protons changes in an atom, a new element will form.

Tin has ten stable isotopes. the heaviest, 124sn, makes up 5.80% of naturally occuring tin atoms. how many atoms of 124sn are present in 82.0 g of naturally occurring tin? what is the total mass of the 124sn atoms in this sample?