The reagent used for converting acetylene to oxalic acid is

Five elements $A, B, C, D$ and $E$ have work functions $1.2\, eV, 2.4\, eV, 3.6\, eV, 4.8\, eV$ and $6\, eV$ respectively. If light of wavelength $4000\, \mathring{A}$ is allowed to fall on these elements,then photoelectrons are emitted by

$A$ glass convex lens $(\mu_g = 1.5)$ has a focal length of $8\,cm$ when placed in air. What would be the focal length of the lens when it is immersed in water $(\mu_w = 1.33)$ (in $,cm$)?

The site where crossing over occurs is known as:

An example of a double salt is

Which one of the following is employed as a tranquilizer drug?