Which among is a black solid?

In brown ring test the  brown  colour is  due to

The  oxidation  state of  s  in oleum is  

The basicity of pyrophosphorus acid is

The group 16 of periodic table is sometimes known as

When ethylalcohol reacts with phosphorous pentachloride which is produced?

The final product obtained by the hydrolysis of phosphorus pentachloride is

The chemical formula of phosphonic acid is

Hypo chlorous  acid  is

Which gas is produced by the thermal decomposition of silver (1)oxide?