On heating ammonium dichromate,the gas evolved is

In the reaction,$2SO_2 + O_2 \xrightarrow[As_2O_3]{Pt} 2SO_3$,$As_2O_3$ acts as:

What is a phycobiont?

For any $y \in R$,let $\cot ^{-1}(y) \in (0, \pi)$ and $\tan ^{-1}(y) \in \left(-\frac{\pi}{2}, \frac{\pi}{2}\right)$. Then the sum of all the solutions of the equation $\tan ^{-1}\left(\frac{6 y}{9-y^2}\right)+\cot ^{-1}\left(\frac{9-y^2}{6 y}\right)=\frac{2 \pi}{3}$ for $0 < |y| < 3$,is equal to

With an increase in atomic number,the melting point of alkali metals .......

$2 \ mol$ of zinc is dissolved in $HCl$ at $25 \ ^\circ C$. The work done in an open vessel is: