I have a few quiz questions that I'm not sure about, if someone could help that'd be great ^^
1. Which of these is a compound?
A) salad
B) carbon dioxide
C) salt water
D) potassium
2. Which of these is a compound?
A) carbon
B) Carbon dioxide
C) air
D) oxygen
3. Which of these is an element?
A) oxygen
B) sodium chloride
C) water
D) air