Arrange benzene,$n$-hexane and ethyne in decreasing order of their acidic behaviour.

In which of the following reactions does an acid-base reaction take place?

What is the major product in the given reaction?

The dibromo compound $[P]$ (molecular formula : $C_{9}H_{10}Br_{2}$) when heated with excess sodamide followed by treatment with dilute $HCl$ gives $[Q]$. On warming $[Q]$ with mercuric sulphate and dilute sulphuric acid yields $[R]$ which gives positive Iodoform test but negative Tollen's test. The compound $[P]$ is:

Give distinguishing tests for the following:
$(a)$ Ethane and ethyne (Alkane and Alkyne $RC \equiv CH$)
$(b)$ Ethene and Ethyne (Alkene and Alkyne $RC \equiv CH$)
$(c)$ Dimethyl ethyne and ethyne
$(d)$ Ethane and Ethene (Alkane and alkene)

Name the distinguishing reaction of an alkane from an alkene.