Use the electron-transfer method to balance this equation:

Zn(s) + HCl(aq) → ZnCl2(aq) + H2(g)

a. 2Zn(s) + HCl(aq) → ZnCl2(aq) + H2(g)

b. Zn(s) + 2HCl(aq) →ZnCl2(aq) + H2(g)

c. Zn(s) + HCl(aq) →ZnCl2(aq) + H2(g)

d. 2Zn(s) + 4HCl(aq) → 2ZnCl2(aq) + 2H2(g)

e. 3Zn(s) + 3HCl(aq) →3ZnCl2(aq) + 3H2(g)

The answer to your question is the letter d.

Explanation:

Data

                Zn  +  HCl   ⇒  ZnCl₂  +  H₂

- Calculate the Oxidation number of reactants and products

              Zn⁰  +  H⁺¹Cl⁻¹   ⇒  Zn⁺²Cl₂⁻¹  +  H₂⁰

- Determine which elements changed their oxidation numbers

                      Zn⁰     ⇒   Zn⁺²                Zn lost 2e⁻

                     2H⁺¹      ⇒   H₂⁰                H won 2 e⁻

-Interchange the electrons lost and won

                  2( Zn⁰     ⇒   Zn⁺²)

                  2(2H⁺¹      ⇒   H₂⁰)

-Simplify

                  2Zn⁰     ⇒   2Zn⁺²

                  4H⁺¹      ⇒   2H₂⁰

-Substitute the coefficient in the equation

                2Zn  +  4HCl   ⇒  2ZnCl₂  +  2H₂  

             Reactant       Element      Product

                  2                    Zn                2

                  4                     H                 4

                  4                     Cl                 4

- Now the reaction is balanced

alfred von schlieffen, german army chief of staff, was given instructions to devise a strategy that would be able to counter a joint attack. in december, 1905, he began circulating what later became known as the schlieffen plan. schlieffen argued that if war took place it was vital that france was speedily defeated.