Chloroform can be obtained from

Consider the following reaction and identify the product $(P)$.

$PCl_5$ reacts with a compound containing

$A$ compound with formula $C_4H_{10}O$ on oxidation gives $C_4H_8O$,which forms an oxime and gives a positive iodoform test. The original compound on reaction with concentrated $H_2SO_4$ gives $C_4H_8$. What is the structure of the compound?

$A$ compound $A$ on oxidation gives acetaldehyde,and further oxidation gives an acid. After the first oxidation,the product reacts with ammoniacal $AgNO_3$ to produce a silver mirror. Compound $A$ is likely to be:

Which of the following shows the Lucas test instantaneously?