Answer:
H₂ + O₂ → H₂O
Now, check that oxygen has two atoms on the left and one on the right
so, you put 2 on the right side
H₂ + O₂ → 2H₂O
oxygen is balanced so, add 2 on H₂ to balance out hydrogen
THE FINAL BALANCED EQUATION:
<h2>
2H₂ + O₂ → 2H₂O</h2>
Answer:

Explanation:
Two important formulas in radioactive decay are

1. Calculate the decay constant k

2. Calculate the mass remaining

Answer is: chemical.
If the arrangement of particles is changed, that is chemical change or chemical reaction (new substance is formed).
In physical change, the bonds between oxygen and hydrogen can not be separated.
For example, balanced chemical reaction: 2Mg(s) + O₂(g) → 2MgO(s).
Chemical changes (chemical synthesis) is when a substance combines with another (in this example magnesium and oxygen) to form a new substance.
Answer:
Carbon fiber if I'm correct