Question

The non-metallic oxide formed when phosphorus burned in oxygen is:
A: ${P_2}{O_5}$
B: ${N_2}O$
C: $C{O_2}$
D: HgO

Answer 1

Hint: Burning of a compound in presence of oxygen is the same as the reaction of that compound with oxygen. Moreover its oxidation state also increases when it reacts with oxygen.

Complete step by step answer:
As we know, Phosphorous is a chemical element with symbol P and atomic number 15. It lies in the 15th group of 3rd period and has electronic configuration $1{s^2}2{s^2}2{p^6}3{s^{^2}}3{p^3}$. Phosphorus exists as a formula ${P_4}$. Elemental phosphorus exists as two major forms i.e. White Phosphorous and Red Phosphorous and is never found as a free element because of its highly reactive nature. Now lets understand about non-metal oxide. The non-metals react with oxygen to form covalent oxide. These oxides are known as non-metal oxides. These oxides react with water to form oxyacids with no change in the oxidation number of the non-metal. The non-metal oxide formed when phosphorus reacts with oxygen is phosphorus pentoxide. The reaction is as follow:-
${P_4} + 5{O_2} \to 2{P_2}{O_5}$
Hence when Phosphorus is burnt in oxygen, phosphorus pentoxide(i.e. ${P_2}{O_5}$) is formed. Hence option A is correct.

Additional Information Phosphorus pentoxide is used as a strong dehydrating agent. It is also used to manufacture optical and heat insulating glass. ${P_2}{O_5}$ is also used in pharmaceuticals and pesticides.

Note:White Phosphorus catches fire spontaneously when it comes in contact with air. Therefore it is kept in water to avoid oxidation by the oxygen present in air.