In the laboratory preparation of oxygen, the gas cannot be collected by downward displacement of air because

  • A the density of oxygen is greater than that of air
  • B the density of air is nearly the same as that of oxygen
  • C oxygen is a component of air
  • D air is an impure substance
jamb 2018chemistry

The correct answer is B. the density of air is nearly the same as that of oxygen

Oxygen is collected in downward displacement of water because:-

Oxygen is only slightly soluble in water. Therefore, it can be collected over water without the fear of excessive dilution.

Oxygen is slightly heavier than air, so it cannot be collected over air.

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