Question

which of the following has the greatest ionization energy? options: o, he, n, cs

Explanation:

Step1: Recall ionization energy trends

Ionization energy generally increases across a period and decreases down a group. Noble gases have high ionization energy due to stable electron configurations.

Step2: Analyze each element

• O (Oxygen): Period 2, Group 16.
• He (Helium): Period 1, Group 18 (noble gas, very stable).
• N (Nitrogen): Period 2, Group 15.
• Cs (Cesium): Period 6, Group 1 (alkali metal, low ionization energy).

Step3: Compare ionization energies

Helium is a noble gas with a full valence shell (1s²), making it very stable. It has a higher ionization energy than O, N, and Cs (which is a large atom with low ionization energy due to its position in the periodic table).

Answer:

He (Helium) has the greatest ionization energy. Among the options, the correct one is the choice with "He".