Molarity is a concentration unit, defined to be the number of moles of solute divided by the number of liters of solution.
<u>Answer:</u> The reactant ratio in the given chemical equation will be: 
<u>Explanation:</u>
Mole ratio is defined as the ratio of the amount of moles of two substances that are participating in a chemical reaction.
In the given chemical equation:

The reactants are Fe and
and the product is 
The mole ratio is basically the stoichiometric ratio of the chemical compounds taking part in a chemical reaction.
The mole ratio of reactants is stoichiometric ratio of Fe and
, which is:

Hence, the reactant ratio in the given chemical equation will be: 
Answer:
The answer is
<h2>3.68 g/mL</h2>
Explanation:
The density of a substance can be found by using the formula
<h3>

</h3>
From the question
mass of substance = 12.50 g
volume = 3.4 mL
The density of the substance is

We have the final answer as
<h3>3.68 g/mL</h3>
Hope this helps you