The formation of osazone from glucose requires 3 moles of phenyl hydrazine. The reaction proceeds in three steps:

1. The first mole of phenyl hydrazine reacts with the aldehyde group (C-1) of glucose to form glucose phenylhydrazone.
2. The second mole of phenyl hydrazine oxidizes the adjacent secondary alcohol group (at C-2) to a ketonic group. During this process, phenyl hydrazine itself gets reduced to aniline and ammonia.
3. The third mole of phenyl hydrazine reacts with this newly formed ketonic group at C-2 to yield the final product, glucosazone (osazone). Therefore, $x = 3$.