Question

question 17
which of the following elements belongs to the p - block?
○ cobalt
○ hydrogen
○ rubidium
○ oxygen

1 pts
question 18
how many valence electrons are found in gallium?
○ 1
○ 5
○ 3
○ 7

Explanation:

For Question 17: Elements in the p - block have their outermost electrons in p - orbitals. Oxygen has its outer - shell electrons in p - orbitals and is in Group 16 (p - block). Cobalt is a d - block element, hydrogen is in the s - block, and rubidium is in the s - block.
For Question 18: Gallium has an atomic number of 31. Its electron configuration is [Ar]3d¹⁰4s²4p¹. The valence electrons are the electrons in the outermost shell, which are 4s²4p¹, so there are 3 valence electrons.

Answer:

Question 17: oxygen
Question 18: 3