What Happens When Dilute Hydrochloric Acid is Added to Iron Filling

Answer: The single displacement reaction occurs when the dilute hydrochloric acid is added to the iron filling. The iron displaces hydrogen by hydrochloric acid in the single displacement process resulting in the end product. 

Acid + Metal → Salt + hydrogen gas

HCl + Fe → FeCl₂ + H₂

Now balance the Equation 

2HCl + Fe → FeCl₂ + H₂