Answer:
After the concentration of H₂ is decreased
H₂+↑Br₂⇒↓2HBr
After the concentration of HBr is increased
↑H₂+↑Br₂⇒2HBr
Explanation:
After the concentration of H₂ is decreased, there will not be enough H₂ to from HBr, so the concentration of HBr will decrease, and the concentration of Br will increase.
After the concentration of HBr is increased, there would be more HBr that will give more H₂ and Br₂.