Question

what appears to be the trend in the first ionization energy as you move from left to right in a period? increasing decreasing remains the same

Explanation:

In the periodic table, as we move from left to right in a period, the atomic number increases, meaning the number of protons in the nucleus increases. This increases the nuclear charge. At the same time, the electrons are added to the same principal energy level (so the shielding effect from inner electrons doesn't change much). The increased nuclear charge pulls the valence electrons more strongly towards the nucleus, making it harder to remove the outermost electron (which is what first ionization energy measures). So the first ionization energy generally shows an increasing trend from left to right across a period.

Answer:

A. increasing