Can anyone explain the reason for this chemistry question?

Question

A 5.0-gram sample of zinc and a 50.-milliliter

sample of hydrochloric acid are used in a

chemical reaction. Which combination of these

samples has the fastest reaction rate?

choices:(1) a zinc strip and 1.0 M HCl(aq)

(2) a zinc strip and 3.0 M HCl(aq)

(3) zinc powder and 1.0 M HCl(aq)

(4) zinc powder and 3.0 M HCl(aq)

Answer:(4) zinc powder and 3.0 M HCl(aq)

Answer 1

The reason the answer is 4 is that the increase surface area of the zinc as a powder increases the reaction rate.  Also, the higher  concentration of acid results in a faster reaction because the higher concentration results in more frequent contact between the zinc particles and the acid (somewhat random in nature, so the higher concentration increases the probability).

Answer 2

The rate of reaction is dependent on the "concentration" of HCl(aq) and zinc. The greatest concentration of both occurs with zinc powder, which has a higher surface-to-weight ratio than zinc strip, and 3.0M HCl, which has the highest concentration of HCl.

Answer 3

Because the Zn powder has he most exposed surface and the 3 M HCl is the strongest.

Answer 4

1.  Surface amount.  The zinc power has more surface area, more zinc atoms on the surface, than a strip of zinc.  More available atoms (or molecules or ions) - the faster the reaction.

2.  3M HCl has three times the amount of H+ available to react.  More ions available the faster the reaction.