Question

2h₂ + o₂ → 2h₂o
tells you the amount of
tells you the amount of
2h₂
two h₂ molecules
2h₂o → 2h₂ + o₂

Explanation:

Step1: Analyze the left - side arrow

The left - side arrow points to the coefficient \(2\) in \(2H_{2}\). In a chemical formula, the coefficient in front of a molecule formula represents the number of molecules. So, \(2H_{2}\) means two hydrogen molecules.

Step2: Analyze the right - side arrow

The right - side arrow points to the subscript \(2\) in \(H_{2}O\). In a chemical formula, the subscript in a molecule formula represents the number of atoms of the element it is attached to. In \(H_{2}O\), the subscript \(2\) next to \(H\) means there are two hydrogen atoms in one water molecule.

Answer:

The left - side arrow (pointing to the coefficient in \(2H_{2}\)) tells you the amount of molecules. The right - side arrow (pointing to the subscript in \(H_{2}O\)) tells you the amount of atoms.