Which method is used to produce nitric acid?

Which of the following is the incorrect order?

Calcium phosphide reacts with water to form $Ca(OH)_2$ and $X$. When $X$ is passed into $CuSO_4$ solution,$Y$ and $H_2SO_4$ are formed. What is $Y$?

Which of the following statements is $NOT$ correct?

Which of the following statements is incorrect for white and red phosphorus?

The number of oxygen atoms bonded to one phosphorus atom in $P_4O_6$ is