Question

how many valence electrons does oxygen have? *
1 point
a. 2
b. 4
c. 6
d. 8
identify the mystery element based on the properties provided. *
1 point
periodic table image mystery element #4

• gas
• full valence electron shells
• colorless
• odorless
• tasteless
• low chemical reactivity

option a
option b
option c
option d

Explanation:

First Question (Valence Electrons of Oxygen)

Step1: Recall Oxygen's Atomic Structure

Oxygen has an atomic number of 8. Its electron configuration is $1s^2 2s^2 2p^4$. The valence electrons are in the outermost shell (n = 2 here), so we sum the electrons in the 2s and 2p subshells: $2 + 4 = 6$.

Step2: Match with Options

The calculated number of valence electrons (6) corresponds to option C.

Elements with full valence electron shells, low chemical reactivity, and being colorless, odorless, tasteless gases are noble gases. Noble gases are in Group 18 (the rightmost group) of the periodic table. Option D is in Group 18 (assuming the periodic table layout: Group 18 elements have full valence shells, are gases, and inert/low reactivity). The properties (gas, full valence shells, colorless, odorless, tasteless, low reactivity) match noble gases, which are in Group 18 (Option D's position).

Answer:

C. 6

Second Question (Mystery Element)