Rate of a Chemical Reaction — JEE Main Chemistry MCQs with Solutions

For the roasting reaction $4FeS_2 + 11O_2 \rightarrow 2Fe_2O_3 + 8SO_2$, at a certain instant $SO_2$ is being formed at $4.0\times10^{-3}\,mol\,L^{-1}s^{-1}$. The rate of consumption of $O_2$ at that instant is:

For the combustion $C_3H_8 + 5O_2 \rightarrow 3CO_2 + 4H_2O$, at an instant $CO_2$ is being formed at $6.0\times10^{-3}\,mol\,L^{-1}s^{-1}$. The rate of consumption of $O_2$ at that instant is:

For a reaction $A \rightarrow$ products the concentration of $A$ varies with time as $[A]=0.50-0.02\,t-0.003\,t^2$ (with $[A]$ in $mol\,L^{-1}$ and $t$ in $s$). The instantaneous rate of disappearance of $A$ at $t=10\,s$ is:

For a reaction the concentration of the reactant $R$ is: $[R]=0.240\,M$ at $t=0$, $0.180\,M$ at $t=30\,s$ and $0.150\,M$ at $t=60\,s$. The average rate of disappearance of $R$ over the first $60\,s$ is:

For a reaction $[A]$ falls uniformly (linearly) from $0.500\,M$ at $t=0$ to $0.300\,M$ at $t=50\,s$. The concentration of $A$ at $t=35\,s$ and the average rate of disappearance over the first $35\,s$ are, respectively:

In a gaseous reaction a reactant is being consumed at $3.0\times10^{-4}\,mol\,L^{-1}s^{-1}$ at a temperature where $RT=20\,L\,atm\,mol^{-1}$. Using $p=CRT$, the rate of decrease of its partial pressure is:

The partial pressure of a gaseous reactant falls at $0.030\,atm\,s^{-1}$ at a temperature where $RT=24\,L\,atm\,mol^{-1}$. The rate of disappearance of the reactant expressed in concentration units is:

For $2A + 3B \rightarrow C + 2D$, the rate of the reaction defined as $r=-\dfrac{1}{2}\dfrac{d[A]}{dt}=-\dfrac{1}{3}\dfrac{d[B]}{dt}=\dfrac{d[C]}{dt}$ equals $1.2\times10^{-3}\,mol\,L^{-1}s^{-1}$. The rate of disappearance of $B$ is:

For the gaseous decomposition $A(g) \rightarrow 2B(g) + C(g)$ carried out in a rigid vessel, the partial pressure of $A$ is falling at $0.010\,atm\,s^{-1}$ at an instant. The rate of increase of the total pressure at that instant is:

For the redox reaction $2MnO_4^- + 5C_2O_4^{2-} + 16H^+ \rightarrow 2Mn^{2+} + 10CO_2 + 8H_2O$, $CO_2$ is evolved at $5.0\times10^{-3}\,mol\,L^{-1}s^{-1}$. The rate of disappearance of $MnO_4^-$ is:

In a reaction the amount of product $x$ (in $mol\,L^{-1}$) formed up to time $t$ (in $s$) is $x=0.4\,t-0.01\,t^2$. The rate of formation of the product at $t=15\,s$ is:

For $A \rightarrow$ products with $[A]_0=0.80\,M$, the fraction of $A$ reacted is $0.20$ at $t=100\,s$ and $0.50$ at $t=250\,s$. The average rate of disappearance of $A$ between $100\,s$ and $250\,s$ is:

For $2H_2S + SO_2 \rightarrow 3S + 2H_2O$, at an instant $H_2S$ is being consumed at $4.0\times10^{-3}\,mol\,L^{-1}s^{-1}$. The rate of formation of sulfur ($S$) at that instant is:

For $2NO_2(g) \rightarrow 2NO(g) + O_2(g)$ in a closed rigid vessel, at an instant $-\dfrac{dp_{NO_2}}{dt}=8.0\times10^{-3}\,atm\,s^{-1}$. The rate of increase of the total pressure at that instant is:

For $A + 3B \rightarrow 2C$ carried out in a $2\,L$ closed vessel, $0.60\,mol$ of $C$ is produced in $50\,s$. The average rate of consumption of $B$ over this period is:

The gaseous reaction $A(g) \rightarrow 3B(g)$ is studied in a rigid vessel starting from pure $A$ at $0.80\,atm$. At an instant when the total pressure is $1.60\,atm$, the total pressure is rising at $0.040\,atm\,s^{-1}$. The rate of disappearance of $A$ (in $atm\,s^{-1}$) at that instant is:

For the gas-phase reaction $2A(g) \rightarrow B(g)$ at $500\,K$ ($R=0.0821\,L\,atm\,K^{-1}mol^{-1}$), the concentration of $A$ is decreasing at $4.0\times10^{-4}\,mol\,L^{-1}s^{-1}$. The rate of increase of the partial pressure of $B$ is:

For $A \rightarrow$ products: $[A]=1.00\,M$ at $t=0$, $0.80\,M$ at $t=40\,s$, $0.65\,M$ at $t=80\,s$. Assuming $[A]$ changes linearly within each $40\,s$ interval, the estimated average rate of disappearance of $A$ between $t=20\,s$ and $t=60\,s$ is:

For a reaction $A \rightarrow$ products the concentration follows $[A]=\dfrac{1}{1+0.5\,t}$ (with $[A]$ in $mol\,L^{-1}$ and $t$ in $s$). The rate of disappearance of $A$ at $t=2\,s$ is:

For $3A \rightarrow 2B$, $[B]$ increases from $0$ to $0.12\,M$ during the first $30\,s$, and the instantaneous rate of formation of $B$ at $t=30\,s$ is $2.0\times10^{-3}\,mol\,L^{-1}s^{-1}$. The instantaneous rate of disappearance of $A$ at $t=30\,s$ is:

For $2A(g) \rightarrow 4B(g) + C(g)$ in a rigid vessel starting from pure $A$ at $p_0=200\,mm\,Hg$, the total pressure at an instant is $350\,mm\,Hg$, and at that instant $p_A$ is falling at $2.0\,mm\,Hg\,s^{-1}$. The fraction of $A$ decomposed and $\dfrac{dp_{tot}}{dt}$ are, respectively:

For $A + 2B \rightarrow 3C$, the rate of the reaction is $r$. At an instant $C$ is being formed at $9.0\times10^{-3}\,mol\,L^{-1}s^{-1}$. The values of $r$ and $-\dfrac{d[B]}{dt}$ at that instant are, respectively:

For $2NO(g) + O_2(g) \rightarrow 2NO_2(g)$ at $500\,K$ ($R=0.0821\,L\,atm\,K^{-1}mol^{-1}$), $NO_2$ is being formed at $4.0\times10^{-5}\,mol\,L^{-1}s^{-1}$. The rate of decrease of the partial pressure of $O_2$ is:

For a reaction $A \rightarrow$ products, $[A]$ (in $M$) follows $[A]=0.60\,e^{-0.05\,t}$ with $t$ in $s$. Using $e^{-0.5}=0.607$, the average rate of disappearance of $A$ over the first $10\,s$ and the instantaneous rate at $t=0$ are, respectively:

In a reaction $aA \rightarrow bB$ it is found that $-\dfrac{d[A]}{dt}=3\left(\dfrac{d[B]}{dt}\right)$ at every instant. If $A$ disappears at $9.0\times10^{-3}\,mol\,L^{-1}s^{-1}$ and the reaction rate (per $r=-\dfrac{1}{a}\dfrac{d[A]}{dt}=\dfrac{1}{b}\dfrac{d[B]}{dt}$) is $1.5\times10^{-3}\,mol\,L^{-1}s^{-1}$, the simplest ratio $a:b$ and $\dfrac{d[B]}{dt}$ are:

For $2SO_2(g) + O_2(g) \rightarrow 2SO_3(g)$ carried out in a rigid vessel, the total pressure is falling at $4.0\times10^{-3}\,atm\,s^{-1}$ at an instant. The rate of consumption of $SO_2$ (partial pressure) at that instant is:

A reaction $2A \rightarrow 3B$ proceeds at a constant rate of reaction $r=5.0\times10^{-4}\,mol\,L^{-1}s^{-1}$ (zero order). Starting with $[A]_0=0.100\,M$ and $[B]_0=0$, the concentration of $B$ after $100\,s$ is:

A gaseous reactant is being consumed at $2.0\times10^{-3}\,mol\,L^{-1}s^{-1}$, which corresponds to a fall in its partial pressure of $0.050\,atm\,s^{-1}$. Taking $R=0.0821\,L\,atm\,K^{-1}mol^{-1}$, the temperature of the reaction is closest to:

For $4A + B \rightarrow 2C + 3D$, at a certain instant $A$ is disappearing at $8.0\times10^{-3}\,mol\,L^{-1}s^{-1}$. The values of $-\dfrac{d[B]}{dt}$, $\dfrac{d[C]}{dt}$ and $\dfrac{d[D]}{dt}$ at that instant are, respectively:

The decomposition $2A(g) \rightarrow B(g) + 3C(g)$ occurs in a rigid $10\,L$ flask at $300\,K$ ($R=0.0821\,L\,atm\,K^{-1}mol^{-1}$). At an instant the total pressure is increasing at $0.090\,atm\,s^{-1}$. The rate of formation of $C$ in concentration units at that instant is: