Why is the reaction of Iron and hydrochloric acid slow ​

The chloride formed when iron reacts with hydrochloric acid is iron (II) chloride, also known as iron dichloride. The reaction between iron and hydrochloric acid is slower than the reaction with zinc, with much smaller hydrogen bubbles produced.

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).