The correct answer among the choices given is option A. Eustachian, Pharynx, Bronchi are structures that ensembles a tube. The Eustachian tube is a narrow passage from the pharynx to the middle ear. Pharynx is a passageway leading from the oral and nasal cavities to the larynx and the esophagus. Lastly, bronchi is an airway in the respiratory tract.
The mass of carbon dioxide that would be made by reacting 30 grams C2H6 with 320 grams O2 will be 80 grams
From the balanced equation of the reaction:

The mole ratio of C2H6 to O2 is 2:7.
- Mole of 30 grams C2H6 = mass/molar mass
= 30/30
= 1 mole
- Mole of 320 grams O2 = 320/32
= 10 moles
Thus, C2H6 is the limiting reactant.
Mole ratio of C2H6 to CO2 according to the equation = 1:2
Since the mole of C2H6 is 1, the equivalent mole of CO2 would, therefore, be 2.
Mass of 2 moles CO2 = mole x molar mass
= 2 x 44
= 88 grams
More on stoichiometric calculations can be found here: brainly.com/question/8062886?referrer=searchResults
The first three quantum numbers for electrons located in subshell 4s are :