What is the term for the body's immediate reaction to a perceived threat, often referred to as the 'fight or flight' response?

Explain the term Ligand.

For the reaction 

$2{\mathrm{N}}_2{\mathrm{O}}_5\left(\mathrm{g}\right)\to 4{\mathrm{NO}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)$,

the rate of formation of ${\mathrm{NO}}_2\left(\mathrm{g}\right)$ is $2.8\times {10}^{-3} {\mathrm{Ms}}^{-1}$. Calculate the rate of disappearance of ${\mathrm{N}}_2{\mathrm{O}}_5\left(\mathrm{g}\right)$.