Which of the following is the formula for metaphosphoric acid?

Which of the following is the incorrect order?

Nitrogen shows different oxidation states in the range of:

Give the preparation of phosphine $(PH_{3})$. State the physical and chemical properties of phosphine $(PH_{3})$. State the uses of phosphine.

Write a balanced chemical equation for the reaction showing catalytic oxidation of $NH_3$ by atmospheric oxygen.

Which of the following oxides of nitrogen is the anhydride of $HNO_3$?