For each of the molecules determine if they have the following center of symmetry, the axis of symmetry and plane of symmetry
a. propane
b. butane
c. ethane

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.

it's c. elements are placed in rows based on how may valencies electrons have.

answers: to make sure that all of the broken pieces of tablet were added to the water, to allow for fair comparison of all three trials, with different particle sizes to avoid experimental error