A beaker contains 1.5 x 10^23 zinc atoms. How many moles of zinc are present in the beaker?

1/4

Explanation:

1.5 * 10^23 atoms zinc * 1 mole zinc/ 6 *10^23 atoms = .25 moles zinc

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.