Which scientist is associated with the term dephlogisticated air for oxygen?

• A. Lavoisier
• B. Priestley
• C. Curie
• D. Dalton

Answer: (B)

Dephlogisticated air is the old name for oxygen. Joseph Priestley produced a gas by heating substances like mercuric oxide and observed that it supported combustion and life more vigorously than ordinary air. He reasoned that air contained a substance called phlogiston, and removing it from air created this “dephlogisticated air.” That labeling is specific to Priestley and his interpretation of how air worked at the time. Later, Lavoisier showed that this gas is a distinct element and gave it the name oxygen, reframing the explanation without the phlogiston idea. So the term in question is tied to Priestley’s work, making him the scientist associated with it.