Correct statement about alkali metal oxides is :

A $$\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{}^{573\,K}} $$ Red phosphorus $$\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{under\,pressure}^{heat\,;\,803\,K}} $$ B

Red phosphorus is obtained by heating "A" at 573 K, and can be converted to "B" by heating at 803 K under pressure.

A and B, respectively, are

Correct formula of the compound which gives a white precipitate with BaCl₂ solution, but not with AgNO₃ solution, is :

Which one of the following chemicals has not been used for the dry cleaning of clothes?