Which of the following statements about a balanced chemical equation is true?

Options

A. mass is conserved
B. atoms are conserved
C. mass as well as atoms are conserved
D. molecules are conserved

Explanation

To determine which statements about a balanced chemical equation are true, we need to understand the key characteristics of such equations. Here’s a step-by-step breakdown:

### Step 1: Definition of a Chemical Equation
A chemical equation is a symbolic representation of a chemical reaction where the reactants are shown on the left side and the products on the right side.

### Step 2: Representation of Reactants and Products
In a balanced chemical equation, both reactants and products are represented in their elemental form, using their molecular formulas. For example, in the reaction of hydrogen and oxygen to form water, we write it as:
\[ \text{H}_2 + \text{O}_2 \rightarrow \text{H}_2\text{O} \]

### Step 3: Conservation of Mass
In a balanced chemical equation, the law of conservation of mass applies. This means that the total mass of the reactants must equal the total mass of the products. Therefore, the number of atoms of each element must be the same on both sides of the equation.

### Step 4: Conservation of Atoms
For a balanced equation, the number of atoms of each element in the reactants must equal the number of atoms of that element in the products. For example, in the balanced equation for the formation of water:
\[ 2 \text{H}_2 + \text{O}_2 \rightarrow 2 \text{H}_2\text{O} \]
Here, there are 4 hydrogen atoms and 2 oxygen atoms on both sides.

### Step 5: Conclusion
From the above points, we can conclude that in a balanced chemical equation:
- The number of atoms is conserved.
- The mass is conserved.
- The equation is balanced in terms of both reactants and products.

### Final Answer
Thus, the true statements about a balanced chemical equation include:
1. The number of atoms on the reactant side equals the number of atoms on the product side.
2. The mass of the reactants equals the mass of the products.