Answer:
4 atoms of oxygen.
Explanation:
The given equation is :

Here Fe and O₂ are reactants and Fe₂O₃ is a product. It is a balanced chemical reaction in which the number of atoms on LHS are equal to number of atoms on RHS.
4 atoms of iron react with 3 atoms of oxygen to form iron oxide. Hence, there are 4 atoms of reactants in this equation.
I believe the answer is A. please let me know if i am correct or not.
The amount remaining at the end of 5 half-lives is 7.81×10¹³ g
From the question given above, the following data were obtained:
- Half-life (t½) = 5730 years
- Original amount (N₀) = 2.5×10¹⁵ g
- Number of half-lives (n) = 5
- Amount remaining (N) =?
The amount remaining can be obtained as follow:
N = 1/2ⁿ × N₀
N = 1/2⁵ × 2.5×10¹⁵
N = 1/32 × 2.5×10¹⁵
N = 0.03125 × 2.5×10¹⁵
N = 7.81×10¹³ g
Therefore, the amount remaining after 5 half-lives is 7.81×10¹³ g
Learn more about half-life: brainly.com/question/25783920
Cl2 is the right answer since the molecule is composed of two chlorines.