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?
X is the effective nuclear charge, and it remains constant down a group.
X is the screening constant, and it remains constant down a group.
X is the effective nuclear charge, and it increases down a group.
X is the screening constant, and it increases down a group.

away from the curb

explanation:

the wheels would then hit the curb if it started to rolling, decreasing the chance of an accident.

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.

the answer is definitely c.

b.

the accuracy of the data.