Which of the following does not act as a neurotransmitter?

The area (in square units) of the triangle formed by the lines $x=0$,$y=0$ and $3x+4y=12$ is:

The final product $(III)$ obtained in the reaction sequence:
$CH_3CH_2COOH$ $\xrightarrow{PCl_3} I$ $\xrightarrow[AlCl_3]{C_6H_6} II$ $\xrightarrow[base, heat]{NH_2NH_2} III$ is

$A$ fish looking up through the water sees the outside world,contained in a circular horizon. If the refractive index of water is $\frac{4}{3}$ and the fish is $12 \ cm$ below the water surface,the radius of this circle in $cm$ is

The oxoacid of sulphur which contains two sulphur atoms in different oxidation states is

Which of the following compounds has the lowest melting point?