Which of the following is a characteristic test for the phenolic group?

Which one of the following elements on doping with germanium,makes it a $p$-type semiconductor?

One gas bleaches the colour of flowers by reduction,while the other by oxidation,the two gases respectively are

The refractive index of the material of a double convex lens is $1.5$ and its focal length is $5 ~cm$. If the radii of curvature are equal,the value of the radius of curvature (in $cm$) is

The total number of possible isomers of the compound $[Cu(NH_3)_4][PtCl_4]$ are:

Which of the following is the correct sequence of the various steps of Herbarium formation?
$1$ Drying $2$ Poisoning $3$ Collection $4$ Labelling $5$ Mounting $6$ Deposition $7$ Stitching