Rate of reaction and factors affecting it — NEET & JEE Questions

Question 1 · difficulty L1 · recall

The rate of a chemical reaction is commonly expressed as the change in concentration of a reactant or product per unit

• A. time
• B. temperature
• C. pressure only
• D. molar mass

Question 2 · difficulty L2 · understanding

$$\mathrm{NO}_2$$ required for a reaction is produced by decomposition of $$\mathrm{N}_2 \mathrm{O}_5$$ in $$\mathrm{CCl}_4$$ as by equation $$2 \mathrm{~N}_2 \mathrm{O}_{5(\mathrm{~g})} \rightarrow 4 \mathrm{NO}_{2(\mathrm{~g})}+\mathrm{O}_{2(\mathrm{~g})}$$ The initial concentration of $$\mathrm{N}_2 \mathrm{O}_5$$ is $$3 \mathrm{~mol} \mathrm{~L}^{-1}$$ and it is $$2.75 \mathrm{~mol} \mathrm{~L}^{-1}$$ after 30 minutes. The rate of formation of $$\mathrm{NO}_2$$ is $$\mathrm{x} \times 10^{-3} \mathrm{~mol} \mathrm{~L}^{-1} \mathrm{~min}^{-1}$$, value of $$\mathrm{x}$$ is _________. (nearest integer)

Question 3 · difficulty L2 · understanding

For a chemical reaction A $$\to$$ B, it was found that concentration of B is increased by 0.2 mol L $$-$$ in 30 min. The average rate of the reaction is ____________ $$\times$$ 10 $$-$$1 mol L $$-$$1 h $$-$$1 . (in nearest integer)

Question 4 · difficulty L2 · understanding

The reaction 2A + B 2 $$\to$$ 2AB is an elementary reaction. For a certain quantity of reactants, if the volume of the reaction vessel is reduced by a factor of 3, the rate of the reaction increases by a factor of ____________. (Round off to the Nearest Integer).

Question 5 · difficulty L2 · understanding

Consider an elementary reaction $$\mathrm{A}(\mathrm{~g})+\mathrm{B}(\mathrm{~g}) \rightarrow \mathrm{C}(\mathrm{~g})+\mathrm{D}(\mathrm{~g})$$ If the volume of reaction mixture is suddenly reduced to $\frac{1}{3}$ of its initial volume, the reaction rate will become ' $x^{\prime}$ times of the original reaction rate. The value of $x$ is :

• A. 3
• B. 9
• C. $\frac{1}{3}$
• D. $\frac{1}{9}$

Question 6 · difficulty L3 · understanding

$$\mathrm{KClO}_{3}+6 \mathrm{FeSO}_{4}+3 \mathrm{H}_{2} \mathrm{SO}_{4} \rightarrow \mathrm{KCl}+3 \mathrm{Fe}_{2}\left(\mathrm{SO}_{4}\right)_{3}+3 \mathrm{H}_{2} \mathrm{O}$$ The above reaction was studied at $$300 \mathrm{~K}$$ by monitoring the concentration of $$\mathrm{FeSO}_{4}$$ in which initial concentration was $$10 \mathrm{M}$$ and after half an hour became 8.8 M. The rate of production of $$\mathrm{Fe}_{2}\left(\mathrm{SO}_{4}\right)_{3}$$ is _________ $$\times 10^{-6} \mathrm{~mol} \mathrm{~L} \mathrm{~s}^{-1}$$ (Nearest integer)

Question 7 · difficulty L3 · understanding

For a given chemical reaction $$\gamma$$ 1 A + $$\gamma$$ 2 B $$\to$$ $$\gamma$$ 3 C + $$\gamma$$ 4 D Concentration of C changes from 10 mmol dm $$-$$3 to 20 mmol dm $$-$$3 in 10 seconds. Rate of appearance of D is 1.5 times the rate of disappearance of B which is twice the rate of disappearance A. The rate of appearance of D has been experimentally determined to be 9 mmol dm $$-$$3 s $$-$$1 . Therefore, the rate of reaction is _____________ mmol dm $$-$$3 s $$-$$1 . (Nearest Integer)

Question 8 · difficulty L3 · understanding

The reaction that occurs in a breath analyser, a device used to determine the alcohol level in a person's blood stream is $$2{K_2}C{r_2}{O_7} + 8{H_2}S{O_4} + 3{C_2}{H_6}O \to 2C{r_2}{(S{O_4})_3} + 3{C_2}{H_4}{O_2} + 2{K_2}S{O_4} + 11{H_2}O$$ If the rate of appearance of Cr 2 (SO 4 ) 3 is 2.67 mol min $$-$$1 at a particular time, the rate of disappearance of C 2 H 6 O at the same time is _____________ mol min $$-$$1 . (Nearest integer)

Question 9 · difficulty L3 · understanding

Observe the following reactions at $\mathrm{T}(\mathrm{K})$. I. $\mathrm{A} \rightarrow$ products. II. $5 \mathrm{Br}^{-}(\mathrm{aq})+\mathrm{BrO}_3{ }^{-}(\mathrm{aq})+6 \mathrm{H}^{+}(\mathrm{aq}) \rightarrow 3 \mathrm{Br}_2(\mathrm{aq})+3 \mathrm{H}_2 \mathrm{O}(\mathrm{l})$ Both the reactions are started at 10.00 am . The rates of these reactions at 10.10 am are same. The value of $-\frac{\Delta\left[\mathrm{Br}^{-}\right]}{\Delta \mathrm{t}}$ at 10.10 am is $2 \times 10^{-4} \mathrm{~mol} \mathrm{~L}^{-1} \mathrm{~min}^{-1}$. The concentration of A at 10.10 am is $10^{-2} \mathrm{~mol} \mathrm{~L}^{-1}$. What is the first order rate constant (in $\mathrm{min}^{-1}$ ) of reaction $I$ ?

• A. $4 \times 10^{-3}$
• B. $2 \times 10^{-3}$
• C. $10^{-3}$
• D. $10^{-2}$

Question 10 · difficulty L3 · understanding

$\mathrm{A} \rightarrow$ product (First order reaction). Three sets of experiment were performed for a reaction under similar experimental conditions: Run $1 \Rightarrow 100 \mathrm{~mL}$ of 10 M solution of reactant A Run $2 \Rightarrow 200 \mathrm{~mL}$ of 10 M solution of reactant A Run $3 \Rightarrow 100 \mathrm{~mL}$ of 10 M solution of reactant $\mathrm{A}+100 \mathrm{~mL}$ of $\mathrm{H}_2 \mathrm{O}$ added. The correct variation of rate of reaction is

• A. Run $1=$ Run $2=$ Run 3
• B. Run $3<\operatorname{Run} 1<\operatorname{Run} 2$
• C. Run $1<$ Run $2<$ Run 3
• D. Run $3<$ Run $1=$ Run 2