Answer : The correct expression will be:

Explanation :
The chemical reactions are :
(1)

(2)

The final chemical reaction is :

Now we have to calculate the value of
for the final reaction.
Now equation 1 is multiply by 2 and then add both the reaction we get the value of 'K'.
If the equation is multiplied by a factor of '2', the equilibrium constant will be the square of the equilibrium constant of initial reaction.
If the two equations are added then equilibrium constant will be multiplied.
Thus, the value of 'K' will be:

The forces of attraction between particles in their gaseous state seems to be nonexistential.
therefore scientist would care less. however another state after gas which is plasma has a lesser force of attraction than the gaseous state.
Answer:
How many grams of H2O are in 1.0 mole of H2O?
18.02 grams
The average mass of one H2O molecule is 18.02 amu. The number of atoms is an exact number, the number of mole is an exact number; they do not affect the number of significant figures. The average mass of one mole of H2O is 18.02 grams.
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Use a ratio to find out that x/190.2 = 74.5/100
hope this helps