Answer:
b. As.
Step-by-step explanation:
The valence electron configuration is 4s²4p³.
The principal quantum number is 4, so the element is in Row 4.
The element has two 4s electrons and three 4p electrons.
- Start at the far left of Row 4.
- Count two squares in the s block.
- Skip the d block (they are inner electrons).
- Count three squares in the p block.
That brings you to Element 33, As.
The element with electron configuration 4s²4p³ is As, arsenic.