How many of the following compounds are less acidic than phenol?

$\mathrm{m}-$nitrophenol, benzyl alcohol, $\mathrm{o}-$cresol, $\mathrm{o}-$chlorophenol, ethanol, picric acid, cyclohexanol

The number of benzene rings in the structure of phenolphthalein are

How many of the following alcohols are secondary in nature?

Butan$-2-\mathrm{ol}, 2,2$ -dimethylpropan$- 1 -\mathrm{ol}$, propan$-1,2-$diol,

methylpropan$-2-\mathrm{ol}$, propan$-1,3-$diol, propan$-2-\mathrm{ol}$, cyclobutanol,

$2-$methylcyclopentanol, propan$-1,2,3-$triol.

${\mathrm{RCH}}_2\mathrm{OH} + {\mathrm{CrO}}_3\stackrel{\mathrm{aq}. {\mathrm{H}}_2{\mathrm{SO}}_4}{\to } \mathrm{Z} + {\mathrm{Cr}}^{\mathrm{x}+}$

The oxidation number $\mathrm{x}$ of $\mathrm{Cr}$will be

Among the following reagents, find out the total number of reagents that will oxidise $1°$ alcohols exclusively to aldehydes.

$\mathrm{Conc}. {\mathrm{HNO}}_3, {\mathrm{KMnO}}_4,/{\mathrm{OH}}^{-}, \mathrm{PCC}, \mathrm{Cu}/573 \mathrm{K},$$\mathrm{PDC}, {\mathrm{MnO}}_2, {\mathrm{K}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7/{\mathrm{H}}^{+}$.

Chlorobenzene $+{\mathrm{H}}_2\mathrm{O}\underset{-\mathrm{HCl}}{\overset{{\mathrm{SiO}}_2, 698 \mathrm{K}}{\to }}\mathrm{X}$ $\stackrel{\mathrm{NaOH}}{\to }\mathrm{Y}\underset{{\mathrm{H}}^{+}}{\overset{{\mathrm{CO}}_2}{\to }}\mathrm{Z}$

Find the number of $\mathrm{\pi }$ bonds in $\text{Z}$.

Phenol $\underset{{\mathrm{H}}_2{\mathrm{SO}}_4}{\overset{{\mathrm{Na}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7}{\to }}\mathrm{X}$

The ratio of the number of sigma to pi bonds in the product $\mathrm{X}$ is: