Explanation:
The atoms of elements on the same period on the periodic table typically have the same number of valence electrons.
They have the same electronic configuration.
Valence electrons are electrons in the outermost shell of an atom.
The number of electrons in an atom is a good indicator of elements that might potentially belong to the same group.
<u>Answer:</u> The coefficient '3' should be placed infront of oxygen gas to balance the oxygen atoms.
<u>Explanation:</u>
Law of conservation of mass states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form.
This also means that total mass on the reactant side must be equal to the total mass on the product side.
A balanced chemical equation is defined as the equation in which total number of individual atoms on the reactant side is equal to the total number of individual atoms on product side.
For the given chemical reaction, the balanced equation follows:

By Stoichiometry of the reaction:
1 mole of ethanol reacts with 3 moles of oxygen gas to produce 2 moles of carbon dioxide gas and 3 moles of water molecule
Hence, the coefficient '3' should be placed infront of oxygen gas to balance the oxygen atoms.
These are diseases that affect primarily the lungs or any other part of the respiratory system.
<h3>What are respiratory disorders?</h3>
The term respiratory disorders refers to those diseases that affect primarily the lungs or any other part of the respiratory system. These are the diseases that prevent a person from breathing in and out normally and prevent the lungs from playing its usual role in gaseous exchange.
The respiratory disorders could be able to make a person not to be able to breathe well and it may lead to hospitalization and death of the patient of adequate treatment is not sought from an expert who could diagnose and treat such respiratory disorders.
The common types of respiratory disorders are;
- asthma
- cystic fibrosis
- emphysema
- lung cancer
- mesothelioma
- tuberculosis
Learn more about respiratory disorder:brainly.com/question/15366562
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Answer: is A
Reason: because the rest are common...