White phosphorus $(P_4)$ has

Which of the following is a cyclic phosphate?

Which of the following reactions is incorrect?

Given below are two statements:
Statement $I$: The halogen that makes the longest bond with hydrogen in $HX$ has the smallest covalent radius in its group.
Statement $II$: $A$ group $15$ element's hydride $EH_3$ has the lowest boiling point among corresponding hydrides of other group $15$ elements. The maximum covalency of that element $E$ is $4$.
In the light of the above statements, choose the correct answer from the options given below.

Which of the following oxyacids has an $X-O-X$ linkage?

Which of the following acids forms two series of salts?