Question 10
An element has the configuration 2, 8. Which group does it belong to?
The right answer is the one marked above.
Group VIII / 0. Its last energy level holds 8 electrons, which is a stable configuration — this is neon, a noble gas.
Group VIII / 0 is the one group not numbered by counting up from one. Everything else follows the count directly: 1 valence electron → group I, 4 → group IV, 7 → group VII. Eight, or any stable arrangement, is where the sequence closes.