Cresol has which of the following functional groups?

In the presence of $NaOH$,phenol reacts with $CHCl_3$ to form $o$-hydroxybenzaldehyde. This reaction is called:

Which of the following is the least acidic?

What does phenol give with $NaOH$ and $CHCl_3$ at $340 \ K$?

The major product in the following reaction is:

Some compounds and their $pK_a$ values are given. Arrange them in decreasing order of their acidic strength.
$(i)$ Ethanol $(15.9)$,Phenol $(10.0)$,Cresol $(10.1)$,Water $(15.7)$
$(ii)$ $o$-Nitrophenol $(7.2)$,$m$-Nitrophenol $(8.3)$,Ethanol $(15.9)$,Water $(15.7)$,Phenol $(10.0)$