What is the product obtained when orthophosphoric acid $(H_3PO_4)$ is heated to a high temperature?

Nitrogen shows different oxidation states in the range of:

The important method for the fixation of nitrogen is

Name the gas that has a smell like rotten fish.

Assertion : White phosphorus is more reactive than red phosphorus.
Reason : Red phosphorus consists of $P_4$ tetrahedral units linked to one another to form linear chains.

Which of the following substances is not an isomorphous true alum and is known as a pseudo alum?