Which of the following reactions is best for the preparation of an aldehyde from a primary alcohol?

The oxidation of toluene to benzaldehyde by chromyl chloride $(CrO_2Cl_2)$ is called:

An organic compound $X$ gives a red precipitate on heating with Fehling's solution. Which one of the following reactions yields $X$ as a major product?

Chromyl chloride converts a methyl group to a chromium complex,which on acid hydrolysis gives the corresponding aldehyde. This reaction is called:

Match the following:
| List-$I$ | List-$II$ |
| :--- | :--- |
| $(A)$ Acid chloride to aldehyde | $(I)$ $DIBAL-H$ |
| $(B)$ Benzene to benzaldehyde | $(II)$ $CO, HCl, \text{anhyd. } AlCl_3$ |
| $(C)$ Acetylene to aldehyde | $(III)$ $HgSO_4, H_2SO_4$ |
| $(D)$ Ester to aldehyde | $(IV)$ $H_2, Pd-BaSO_4$ |

What is the major product obtained when calcium acetate and calcium formate are heated together?