Which of the following chemical equations best represents the law of conservation of mass?

• A. N_2 + 3H_2 ightarrow 2NH_3 + H_2
• B. C + O_2 ightarrow CO
• C. Na + Cl_2 ightarrow NaCl_2
• D. 2H_2 + O_2 ightarrow 2H_2O

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction. This means the total number of atoms of each element must be the same on both sides of the chemical equation.
2. Step 2: Examine each given chemical equation and count the number of atoms of each element on the reactant side and the product side.
3. Step 3: For the equation \(\mathrm{N_2 + 3H_2 \rightarrow 2NH_3 + H_2}\), count nitrogen and hydrogen atoms on both sides to check if they are balanced.
4. Step 4: For the equation \(\mathrm{C + O_2 \rightarrow CO}\), count carbon and oxygen atoms on both sides to verify if the equation is balanced.
5. Step 5: For the equation \(\mathrm{Na + Cl_2 \rightarrow NaCl_2}\), count sodium and chlorine atoms on both sides to see if the number of atoms is conserved.