The answer is one dot.
The number of dots an element has represented in the diagram, indicates how many valence eletrons( which is the number of electrons in the most exterior energy level of an atom or ion) the element has. So, 1 valence eletron equals one dot.
You can use P1V1/T1 = P2V2/T2 but since pressure is constant is becomes V1/T1=V2/T2
V1=0.5 L
T1=203 K
T2=273 K
V2=unknown
0.5L/203 = V2/273
V2= 0.67 L so C
Hope this helps :)
According to the task, you are proveded with patial pressure of CO2 and graphite, and here is complete solution for the task :
At first you have to find n1 =moles of CO2 and n2 which are moles of C
<span>The you go :
</span>

n1 n2 0
-x -x +2x

After that you have to use the formula

Then you have to solve x, and for that you have to use <span>RT/V
And to find total values:</span>

I am absolutely sure that this would be helpful for you.
Answer:
K I will attempt
Explanation:
a)

b)
1 : 2 : 2 (I don't know if this is what the question wants but it is what I would answer)
c)
Hydrogen because it requires 2 moles of H2 to react with 1 mole of O2
d)
24 moles of water. Look at stoichiometric coefficient. 2:2 means 24 moles you get 24 moles
e)
Oxygen. 2 < 5/2. Remember, 1 mole of O2 requires 2 moles of H2. But 5/2 is still greater than 2
f)
First, let's find out how many moles of water we can get. Since O2 is the limiting reactant, and O2:H2O ratio is 1:2, we will get 4 moles of H2O. Then, we can multiply 4 by Avogadro's number which is
to get the number of molecules. We get: 2.41 * 10^24 molecules of water.