Ethylidene dichloride can be prepared by the reaction of $HCl$ and

Which one of the following carbonyl compounds cannot be prepared by addition of water on an alkyne in the presence of $HgSO_4$ and $H_2SO_4$?

The ozonolysis $(O_3, H_2O)$ of $(CH_3)_2CH-C \equiv C-CH_3$ gives:

The acidic hydrogen is present in $ . . . . . . $.

Identify the alkyne in the following sequence of reactions:
Alkyne $\xrightarrow{\text{H}_2, \text{Lindlar's catalyst}} A$ $\xrightarrow{\text{Ozonolysis}} B \text{ (only)}$
Given that $B$ is obtained from $\text{CH}_2=\text{CH}_2$ via the Wacker process.

$A$ compound $C_5H_8$ gives a white precipitate with ammoniacal $AgNO_3$. It yields $(CH_3)_2CHCOOH$ upon oxidation with hot alkaline $KMnO_4$. The compound is: