Pyrosilicate ion is

Reaction of $NaCl$ with conc. $H_2SO_4$ liberates a gas,$X$ that turns moist blue litmus paper red. When gas $X$ is passed into a test tube containing egg shell powder suspended in water,another gas,$Y$ is generated which when passed through lime water makes it milky. The gases $X$ and $Y$,respectively,are

Anhydrous mercurous chloride can be prepared by

Which of the following oxidation states are the most characteristic for lead and tin respectively?

$PbI_4$ does not exist because

Which of the following gas mixtures is used by divers inside the sea?