Answer
a. Sodium
b. Strontium
c. Germanium
d. Selenium
Work Step by Step
a. Atomic radius increases when moving down a group so since sodium is farther down then lithium in Group 1A on the periodic table it has a larger atomic radius
b. Atomic radius increases when moving down a group so since strontium is farther down then magnesium in Group 2A it has a larger atomic radius
c. Atomic radius increases when moving down a group so since germanium is farther down then carbon in Group 4A it has a larger atomic radius
d. Atomic radius increases when moving down a group so since selenium is farther down then oxygen in Group 6A it has a larger atomic radius
