Question 4 (4 points) (02.07 MC)
Read the given expression.
X = number of protons - number of core electrons
Which of the following explains the identity of X and its trends across a period? (5
points)
1) X is the effective nuclear charge, and it remains constant across a period.
2) X is the screening constant, and it remains constant across a period.
3) X is the effective nuclear charge, and it increases across a period.
4) X is the screening constant, and it increases across a period.