How many atoms of lithium are in 2.5 moles

1.50x10²⁴ atoms of Li are contained in 2.5 mol of it

Explanation:

NA (Avogadro's number) is the number of particles that occupy 1 mol, of anything. Let's do a rule of three:

1 mol of Li has 6.02x10²³ atoms

2.5 moles of Li have ( 2.5 .NA) /1 =1.50x10²⁴

imma come back to you hold on

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.