Which of the following actions is permitted when balancing a chemical equation?

• A. Altering the subscripts within chemical formulas
• B. Changing the coefficients in front of chemical formulas
• C. Changing the physical states (solid, liquid, gas) of the compounds
• D. Adding or removing elements from the reactants or products

Answer: (B)

Verified step by step guidance

1. Understand that balancing a chemical equation means making sure the number of atoms of each element is the same on both sides of the equation, obeying the Law of Conservation of Mass.
2. Recognize that altering the subscripts within chemical formulas changes the actual substances involved, which is not allowed because it changes the identity of the compounds.
3. Know that changing the physical states (solid, liquid, gas) of the compounds does not affect the balancing of atoms; it is a descriptive detail and does not help balance the equation.
4. Realize that adding or removing elements from the reactants or products changes the chemical reaction itself and is not permitted when balancing an equation.
5. Therefore, the only permitted action when balancing a chemical equation is changing the coefficients in front of chemical formulas, which adjusts the number of molecules or moles without altering the substances themselves.