What is the rate of reaction?

Ammonia and oxygen react at high temperature as $4 NH_{3(g)} + 5 O_{2(g)} \longrightarrow 4 NO_{(g)} + 6 H_2 O_{(g)}$. If the rate of formation of $NO_{(g)}$ is $3.6 \times 10^{-3} \ mol \ L^{-1} \ s^{-1}$,then the rate of disappearance of ammonia is:

$A \rightarrow B$ is a first order reaction. The concentration of $A$ is decreased from $x \ mol \ L^{-1}$ to $y \ mol \ L^{-1}$ in $100 \ \min$. What is the average velocity of the reaction in $mol \ L^{-1} \ \min^{-1}$?

Explain the relation between the rate of reaction and the stoichiometric coefficients of a balanced chemical equation with examples.

The rate of disappearance of $MnO_4^-$ in the following reaction is $4.56 \times 10^{-3} \ M/s$.
$2MnO_4^- + 10I^{-} + 16H^{+} \to 2Mn^{2+} + 5I_2 + 8H_2O$
The rate of appearance of $I_2$ is:

Write the rate equation for the following reactions:
$1.$ $2 N_2 O_{5(g)} \rightarrow 4 NO_{2(g)} + O_{2(g)}$
$2.$ $2 HI_{(g)} \rightarrow H_{2(g)} + I_{2(g)}$