What is Schiff's reagent?

Which is the major product obtained by hydrolysis of the compound formed by the reaction between formaldehyde and ethyl magnesium bromide?

$CH_3COOH$ $\xrightarrow{LiAlH_4} X$ $\xrightarrow{Cu, 300^{\circ}C} Y$ $\xrightarrow{\text{Dilute } NaOH} Z$. In the above reaction,$Z$ is:

$A$ mixture of $PhCHO$ and $HCHO$ is treated with $NaOH$. Which of the following processes occur during the Cannizzaro reaction?

Acetaldehyde $(CH_3CHO)$ reacts with:

The reagent used in Wolff-Kishner reduction is