Question

which reaction type is the following? *
zn + 2hcl → zncl₂ + h₂

○ single replacement

○ synthesis

○ combustion

○ double replacement

what type of reaction is this and what are the correct coefficients? *
_ na₂co₃ → _ na₂o + ___ co₂

○ decomposition; na₂co₃ → na₂o + co₂

○ synthesis; na₂co₃ → na₂o + co₂

○ decomposition; 2na₂co₃ → na₂o + co₂

○ double replacement; na₂co₃ → na₂o + co₂

Explanation:

First Question:

Step1: Recall reaction types

Single replacement: \( A + BC
ightarrow AC + B \) (element replaces part of compound). Synthesis: \( A + B
ightarrow AB \). Combustion: involves \( O_2 \), produces \( CO_2 + H_2O \). Double replacement: \( AB + CD
ightarrow AD + CB \) (ions swap).

Step2: Analyze \( \text{Zn} + 2\text{HCl}

ightarrow \text{ZnCl}_2 + \text{H}_2 \)
Zn (element) replaces H in HCl, forming ZnCl₂ and H₂ (element). Matches single replacement pattern (\( A + BC
ightarrow AC + B \), where A=Zn, B=H, C=Cl).

Step1: Identify reaction type

Decomposition: \( AB
ightarrow A + B \) (compound breaks into simpler substances). Synthesis: \( A + B
ightarrow AB \). Here, \( \text{Na}_2\text{CO}_3 \) breaks into \( \text{Na}_2\text{O} \) and \( \text{CO}_2 \), so decomposition.

Step2: Balance the equation

Count atoms: Na: 2 on left, 2 on right (in \( \text{Na}_2\text{O} \)). C: 1 on left, 1 on right (in \( \text{CO}_2 \)). O: 3 on left (1 in \( \text{Na}_2\text{CO}_3 \): 3 O), 1 (in \( \text{Na}_2\text{O} \)) + 2 (in \( \text{CO}_2 \)) = 3 O. So coefficients: 1, 1, 1. The equation \( \text{Na}_2\text{CO}_3
ightarrow \text{Na}_2\text{O} + \text{CO}_2 \) is balanced.

Answer:

A. Single Replacement

Second Question: