Select the correct answer.

Which of the following is a correctly balanced equation?

A. [tex]NaClO_3 \rightarrow NaCl + 3O_2[/tex]

B. [tex]2HgO \rightarrow 2Hg + O_2[/tex]

C. [tex]2ZnS + O_2 \rightarrow 2ZnO + 2SO_2[/tex]

D. [tex]4CO + Fe_3O_4 \rightarrow 4CO_2 + Fe[/tex]

E. [tex]2Fe + 2Cl_2 \rightarrow 2FeCl_3[/tex]



Answer :

To determine which of the given chemical equations is correctly balanced, we'll need to check each equation to ensure that the number of atoms for each element is equal on both the reactant and product sides. Here's the step-by-step evaluation of each option:

### Option A: [tex]\( \text{NaClO}_3 \rightarrow \text{NaCl} + 3\text{O}_2 \)[/tex]

Reactants:
- Na: 1
- Cl: 1
- O: 3

Products:
- Na: 1
- Cl: 1
- O: [tex]\(3 \times 2 = 6\)[/tex]

This equation is not balanced because there's an unequal number of oxygen atoms on each side of the equation.

### Option B: [tex]\( 2\text{HgO} \rightarrow 2\text{Hg} + \text{O}_2 \)[/tex]

Reactants:
- Hg: 2
- O: 2

Products:
- Hg: 2
- O: 2

This equation is balanced because the number of atoms for each element is the same on both sides.

### Option C: [tex]\( 2\text{ZnS} + \text{O}_2 \rightarrow 2\text{ZnO} + 2\text{SO}_2 \)[/tex]

Reactants:
- Zn: 2
- S: 2
- O: 2

Products:
- Zn: 2
- S: 2
- O: [tex]\(2 \times 2 + 2 \times 2 = 4 + 4 = 8 \)[/tex]

This equation is not balanced because the number of oxygen atoms is not equal on both sides.

### Option D: [tex]\( 4 \text{CO} + \text{Fe}_3\text{O}_4 \rightarrow 4 \text{CO}_2 + \text{Fe} \)[/tex]

Reactants:
- C: 4
- O: [tex]\(4 + 4 \times 1 = 4 + 4 = 8 \)[/tex]
- Fe: 3

Products:
- C: 4
- O: [tex]\(4 \times 2 = 8\)[/tex]
- Fe: 1

This equation is not balanced because the number of iron (Fe) atoms is not the same on both sides.

### Option E: [tex]\( 2\text{Fe} + 2\text{Cl}_2 \rightarrow 2\text{FeCl}_3 \)[/tex]

Reactants:
- Fe: 2
- Cl: [tex]\(2 \times 2 = 4\)[/tex]

Products:
- Fe: 2
- Cl: [tex]\(2 \times 3 = 6\)[/tex]

This equation is not balanced because the number of chlorine atoms is not equal on both sides.

### Result

Based on our evaluations, option B:

[tex]\[ 2\text{HgO} \rightarrow 2\text{Hg} + \text{O}_2 \][/tex]

is the correctly balanced equation.