In the laboratory preparation of oxygen, the gas cannot be collected by downward displacement of air because
- the density of oxygen is greater than that of air
-
the density of air is nearly the same as that of oxygen
- oxygen is a component of air
- air is an impure substance
The correct answer is: B
Explanation
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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