What gas will form when you place iron and tin in 1.0 mol/L hydrochloric acid?
H₂ will form when Fe and Sn are placed in 1.0 mol/L HCl.
We can use the activity series to predict which metals will react with HCl.
Any metal will displace an element that is below it in the activity series.
We see that iron and tin are above hydrogen, so they will produce hydrogen gas when placed in 1.0 mol/L HCl.