Answer:
- Kc remains the same.
- Qc increases.
- The reaction will move in the reverse direction.
- The concentration of iodine will decrease.
Explanation:
Hello,
In this case, given the equilibrium:

- We first must state that Kc remains the same as it a function of the temperature only and temperature is not changing.
- Then since 0.4 moles of hydrogen are added, and the reaction quotient Qc is:
![Qc=\frac{[H_2][I_2]}{[HI]^2}](https://tex.z-dn.net/?f=Qc%3D%5Cfrac%7B%5BH_2%5D%5BI_2%5D%7D%7B%5BHI%5D%5E2%7D)
By increasing the concentration of hydrogen, the reaction quotient increases as well due to their directly proportional relationship.
- Due to that addition, the reaction will move in the reverse direction, as more HI must be formed to reestablish the equilibrium.
- Finally, due to the addition of hydrogen, more iodine will be consumed to reestablish equilibrium, for that reason, the concentration of iodine will decrease.
Best regards.