Can u explain it more plz.
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.
Standardized means that a specific amount EDTA is added to a specific volume of distilled water. Water hardness is determined by the the amount of a standard EDTA solution to change the color of the water from red to blue. For example if one added the correct amount of EDTA to twice the volume of distilled water the solution would be weak. Titration of the hard water would give a erroneous high result.
I've put in some of the answers.
hope this helps :)
The region where an electron is most likely to be is called an orbital
