In the reversible reaction,a catalyst is the substance which:

The equilibrium constant for the reaction $N_{2(g)} + O_{2(g)} \rightleftharpoons 2 NO_{(g)}$ is $4 \times 10^{-4}$ at $2000 \ K$. In the presence of a catalyst, the equilibrium is attained $10$ times faster. Therefore, the equilibrium constant, in the presence of the catalyst at $2000 \ K$ is:

In a reversible reaction at equilibrium between two reactants,if the concentration of the reactants is doubled,the equilibrium constant ..........

Identify which of the following reactions represent homogeneous and heterogeneous equilibria:
$(a)$ $H_{2(g)} + I_{2(g)} \rightleftharpoons 2HI_{(g)}$
$(b)$ $Ca(OH)_{2(s)} \rightleftharpoons Ca^{2+}_{(aq)} + 2OH^{-}_{(aq)}$
$(c)$ $CaCO_{3(s)} \rightleftharpoons CaO_{(s)} + CO_{2(g)}$
$(d)$ $Ag_{2}O_{(s)} + 2H^{+}_{(aq)} \rightleftharpoons H_{2}O_{(l)} + 2Ag^{+}_{(aq)}$
$(e)$ $NH_{3(g)} + H_{2}O_{(l)} \rightleftharpoons N{H_{4}}^{+}_{(aq)} + OH^{-}_{(aq)}$
$(f)$ $CH_{3}COOC_{2}H_{5(l)} + H_{2}O_{(l)} \rightleftharpoons CH_{3}COOH_{(l)} + C_{2}H_{5}OH_{(l)}$

In the reaction $PCl_{5(g)} \rightleftharpoons PCl_{3(g)} + Cl_{2(g)}$,a graph is plotted to show the variation of the rate of forward and backward reactions against time. Which of the following is correct?

Explain the dynamic nature of a chemical system in the laboratory using an activity.