​What is the trend for the atomic number while moving across a period in the modem periodic table?​

Correct option is D

The correct answer is (D) the atomic number increases by one unit.

• Atomic size Trends The term "atomic radius" refers to the distance that separates an atom's outermost shell from its center in the nucleus.
• As we move from one period to the next, the addition of shells to an atom makes it larger as a group.
• Atomic size decreases over time as nuclear charge increases while the number of shells stays the same.
• Because of this, electrons are pulled toward the nucleus from the outermost shell, reducing its size.