What is $X$ in the given reaction?

In the Liebermann nitroso reaction,what is the sequence of color changes observed in phenol?

At low temperature,phenol reacts with $Br_2$ in $CS_2$ to form:

Which of the following is the most acidic?

Which of the following is the correct decreasing order of acidic strength for the compounds listed below?
$I$: $p$-chlorophenol
$II$: $p$-Cresol
$III$: $p$-nitrophenol
$IV$: $p$-methoxyphenol

Which one of the following compounds will readily react with dilute $NaOH$?