Question

which list arranges the elements na, li, k, rb, and cs in order of increasing ionization energy (from left to right)?
o na, li, k, rb, cs
o li, na, k, rb, cs
o cs, li, na, k, rb
o cs, rb, k, na, li

Explanation:

Step1: Recall ionization - energy trend

Ionization energy decreases down a group in the periodic table.

Step2: Locate elements in periodic table

Na, Li, K, Rb, Cs are all in Group 1 (alkali metals).

Step3: Determine order of ionization energy

As we go down Group 1 from Li to Cs, ionization energy decreases. So, the order of increasing ionization energy is Cs, Rb, K, Na, Li.

Answer:

Cs, Rb, K, Na, Li