The principle states that the lowest-energy orbitals are filled first, followed ... electron configuration The arrangement of electrons in an atom, molecule, or other ... and two valence electrons (electrons in the outer shell), respectively; because of this, ... mechanics, a certain energy is associated with each electron configuration.
The answer is the 3. Hope this helped!
Answer:
Fe₂O₃ and C are reactants
Fe and CO₂ are products
Explanation:
Reactants:
Chemical species that are present on left side of chemical reaction equation are called reactants.
Product:
Chemical species that are present on right side of chemical reaction equation are called product.
Chemical equation:
2Fe₂O₃ + 3C → 4Fe + 3CO₂
In this reaction 2 mole of iron oxide is react with three moles of carbon and produced four moles of iron and three moles of carbon dioxide. There are equal numbers of atoms of all elements present on both side of chemical reaction so this reaction follow the law of conservation of mass.
Law of conservation of mass:
According to the law of conservation mass, mass can neither be created nor destroyed in a chemical equation.
Explanation:
This law was given by french chemist Antoine Lavoisier in 1789. According to this law mass of reactant and mass of product must be equal, because masses are not created or destroyed in a chemical reaction.
511.2 grams of chlorine gas consumed (with excess H-) when
1,342.0 kJ of energy is released from the system.
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What is an exothermic reaction?</h3>
In thermochemistry, an exothermic reaction is a "reaction for which the overall standard enthalpy change ΔH⚬ is negative."
Given that 1 mole of chlorine releases -184.6 energy.
Then, we have to find the number of moles of chlorine when 1,342.0 kJ of energy is released from the system.
So, calculating number of moles of chlorine.
Moles = 
Moles = 7.2 mole
Now, calculating number mass of chlorine.

Mass = 7.2 mole x 71 g/mole
Mass = 511.2 gram
Learn more about exothermic reaction here:
brainly.com/question/10373907
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