An inorfanic compound (X) made up of two most occurring elements in the earth`s crust and used in bulding construction . When (X ) reacts with carbon . It forms a posionous gas (Y) which is most stable disatomic molecule . Identicy compounds (X ) and (Y) .

Explanation

Give : (X) is made of two most occurring elecments in the earth's crust and used in buliding construction. Hence (X) consiste of Si and oxygen I,e, `SiO_2`
`(X) overset (C)(rarr) (Y)`
a poisonous gas, which is most stable diatomic molecule ,
This implies that (Y) is `CO`.
`SiO_2 + 2 C rarr Si + 2 CO`
`CO` is a poisonous gas and a stavbel diatiomic molecule
Hence (X) is `SiO_2` silica or silicon dioxide.
(Y) is `CO-` , carbobn monoide .