Answer:
At equilibrium, the concentration of  is going to be 0.30M
 is going to be 0.30M
Explanation:
We first need the reaction. 
With the information given we can assume that is:
 +
 +  ⇄ 2
 ⇄ 2
If there is placed 0.600 moles of NO in a 1.0-L vessel, we have a initial concentration of 0.60 M NO; and no  nor
 nor   present. Immediately,
 present. Immediately,  and
 and are going to be produced until equilibrium is reached.
 are going to be produced until equilibrium is reached.
By the ICE (initial, change, equilibrium) analysis:
I: [ ]=0   ;     [
]=0   ;     [ ]= 0    ; [
 ]= 0    ; [ ]=0.60M
]=0.60M
C: [ ]=+x   ;     [
]=+x   ;     [ ]= +x    ; [
 ]= +x    ; [ ]=-2x
]=-2x
E: [ ]=0+x   ;     [
]=0+x   ;     [ ]= 0+x   ; [
 ]= 0+x   ; [ ]=0.60-2x
]=0.60-2x
Now we can use the constant information:
![K_{c}=\frac{[products]^{stoichiometric coefficient} }{[reactants]^{stoichiometric coefficient} }](https://tex.z-dn.net/?f=K_%7Bc%7D%3D%5Cfrac%7B%5Bproducts%5D%5E%7Bstoichiometric%20coefficient%7D%20%7D%7B%5Breactants%5D%5E%7Bstoichiometric%20coefficient%7D%20%7D)
 
 
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= 
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= 
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At equilibrium, the concentration of  is going to be 0.30M
 is going to be 0.30M