The reagent with which both acetaldehyde and acetone react is

Consider the following reaction sequence:
$\text{But-2-ene}$ $\xrightarrow{\text{ozonolysis}} X$ $\xrightarrow[(ii) H_3O^+]{(i) CH_3MgBr} Y$ $\xrightarrow[573 \ K]{Cu} Z$
The correct statements about $Z$ are:
$I$. It gives yellow precipitate with $I_2$ and $NaOH$ solution.
$II$. It undergoes disproportionation reaction in the presence of concentrated $NaOH$ solution.
$III$. It undergoes Wolff-Kishner reduction.
$IV$. It forms red precipitate with Fehling's reagent.

Product $(Q)$ is :-

The reaction of acetaldehyde with conc. $KMnO_4$ gives

Reduction of $>C=O$ to $CH_2$ can be carried out with:

The polymer shown in the image is obtained when a carbon compound is allowed to stand. It is a white solid. The polymer is: