Chemistry

Question Analysis
This question involves comparing first ionization energies of Period 4 elements. The main focus is on applying the basic left-to-right period trend for ionization energy.

Key Concept Explanation
Across a period, as atomic number increases, the nuclear charge increases and the atomic radius decreases. Valence electrons are held more tightly by the nucleus, so more energy is required to remove an electron. Thus, ionization energy increases from left to right across a period.

Step-by-Step Solution
1. All options are in Period 4 of the periodic table.
2. Their positions from left to right: K → Ca → Sc → Ti.
3. Apply the period trend: ionization energy increases left to right.
4. Titanium (Ti...