The correct description for an atom of helium would be option C. An atom of helium has its valence electrons in its first energy level, it wouldn't and can't satisfy the Octet rule as it only has 2 electrons, but with 2, it has a full shell, as the first energy level can hold only 2 electrons.
Answer: There are 4.375 moles in 2.5 L of 1.75 M 
Explanation:
To calculate the number of moles for given molarity, we use the equation:
Molarity of solution = 1.75 M
Volume of solution = 2.5 L
Putting values in equation , we get:

Answer:
28.8km/h
Explanation:
Change the 5min to hours.
=5/60 =0.0833hrs
Velocity= Distance /Time
2.4/0.0833
=28.8km/h
Notice how the K and Ag are both being swapped around.
Single Replacement:
A+BX → B+AX
Double Replacement:
AX+BY → BX + AY
Organic molecules typically do not contain the noble gases, so they would contain all but Ne