3. Which of these is a single replacement reaction? 2H_(2)+O_(2)arrow 2H_(2)O NaOH+HClarrow NaCl+H_(2)O 2KClO_(3)arrow 2KCl+3O_(2) Fe+CuCl_(2)arrow FeCl_(2)+Cu

The correct answer is: $Fe+CuCl_{2}\rightarrow FeCl_{2}+Cu$<br /><br />Explanation: A single replacement reaction involves one element replacing another element in a compound. In the reaction $Fe+CuCl_{2}\rightarrow FeCl_{2}+Cu$, iron (Fe) replaces copper (Cu) in copper(II) chloride (CuCl_{2}), forming iron(II) chloride (FeCl_{2}) and copper (Cu).