Question

which chemical equation represents a double replacement reaction?
a agno₃ + nacl → agcl + nano₃
b zn + 2hcl → zncl₂ + h₂
c 2c₂h₆ + 7o₂ → 4co₂ + 6h₂o
d br₂ + 2ki → 2kbr + i₂

Explanation:

Step1: Recall double - replacement reaction definition

In a double - replacement reaction, the positive and negative ions of two ionic compounds exchange partners.

Step2: Analyze option A

In \(AgNO_3+NaCl\), \(Ag^+\) (from \(AgNO_3\)) combines with \(Cl^-\) (from \(NaCl\)) to form \(AgCl\), and \(Na^+\) (from \(NaCl\)) combines with \(NO_3^-\) (from \(AgNO_3\)) to form \(NaNO_3\). Ions exchange partners.

Step3: Analyze option B

\(Zn + 2HCl\to ZnCl_2 + H_2\) is a single - replacement reaction. \(Zn\) (a metal) replaces \(H\) in \(HCl\).

Step4: Analyze option C

\(2C_2H_6+7O_2\to4CO_2 + 6H_2O\) is a combustion reaction. Hydrocarbon (\(C_2H_6\)) reacts with \(O_2\) to produce \(CO_2\) and \(H_2O\).

Step5: Analyze option D

\(Br_2 + 2KI\to2KBr + I_2\) is a single - replacement reaction. \(Br_2\) (a non - metal) replaces \(I^-\) in \(KI\).

Answer:

A. \(AgNO_3 + NaCl \to AgCl + NaNO_3\)