Question

how does atomic radius change from left to right across a period in the periodic table?
it first increases, then decreases.
it tends to decrease.
it first decreases, then increases.
it tends to increase.

Explanation:

As we move from left to right across a period in the periodic table, the number of protons in the nucleus increases (nuclear charge increases). The electrons are added to the same principal energy level. The increased nuclear charge pulls the electrons closer to the nucleus, reducing the atomic radius.

Answer:

It tends to decrease.