Read the given expression.
x = atomic number − number of core electrons
which of the following explains the identity of x and its trends down a group?
a). x is the effective nuclear charge, and it remains constant down a group.
b). x is the screening constant, and it remains constant down a group.
c). x is the effective nuclear charge, and it increases down a group.
d). x is the screening constant, and it increases down a group.

they it depends on if one believes about radioactivity, they make a geiger counter beep but maybe it was going to beep anyway electronics do wierd things all the time or it was programmed to beep near certain metals.

frequency, z, and the collision density, z, in carbon dioxide (co2), r 180 pm at 30 °c and 120 kpa

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.