1. the amount of zinc required to produce 1.12ml of hydrogen gas (H2) at STP on treatment with dilute hydrochloric acid will be in how many grams?

The reaction is as follows:

Zn + 2HCl ------> ZnCl₂ + H₂

Thus 1 mol Zn produces 1 mol H₂

1 mol of Zn occupies 22.4 mL H₂ gas

Therefore, 1.12 mL of H₂ gas correspond to 0.05 moles of H₂ gas

Thus 0.05 moles of H₂ gas will be produced from 0.05 moles of Zn

1 mol of Zn = 65.38 g

Hence, 0.05 moles of Zn = 3.27 g Zn

Thus, 3.27 g Zn is required to produce 1.12 mL H₂ at STP.