In a first order reaction, the concentration of the reactant, decreases from 0.8 M to 0.4 M in 15 min. The time taken for the concentration to change from 0.1 M to 0.025 M is

• 30 min

• 15 min

• 7.5 min

• 160 min

In a reaction, A + B → C, the rate expression is R = k [A][B]². If the concentration of both the reactant is doubled at constant volume, then the rate of the reaction will be

• eight times

• double

• quadruple

• triple

Which graph represents the zero order reaction [A (g) → B (g)]

$$\begin{gathered} \mathrm{For} \mathrm{the} \mathrm{reaction}, \\ 5{\mathrm{Br}}^{-}\left(\mathrm{aq}\right) + {\mathrm{BrO}}_3^{-}\left(\mathrm{aq}\right) + 6{\mathrm{H}}^{+}\left(\mathrm{aq}\right) \to 3{\mathrm{Br}}_2\left(\mathrm{aq}\right) + 3{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) \\ \mathrm{If}, -\frac{∆\left[{\mathrm{Br}}^{-}\right]}{∆\mathrm{t}}= 0.05 \mathrm{mol} {\mathrm{L}}^{-1} {\min }^{-1}, -\frac{∆\left[{\mathrm{BrO}}_3^{-}\right]}{∆\mathrm{t}} \mathrm{in} {\mathrm{molL}}^{-1} {\min }^{-1} \mathrm{is} \end{gathered}$$

• 0.005

• 0.05

• 0.5

• 0.01

For the reaction $5{\mathrm{Br}}^{-}\left(\mathrm{aq}\right) + 6{\mathrm{H}}^{+}\left(\mathrm{aq}\right) + {\mathrm{BrO}}_3^{-} \to 3{\mathrm{Br}}_2\left(\mathrm{aq}\right) + 3{\mathrm{H}}_2\mathrm{O} \left(\mathrm{l}\right) \mathrm{if}, -\frac{∆\left[{\mathrm{BrO}}_3^{-}\right]}{∆\mathrm{t}}= 0.01 \mathrm{mol} {\mathrm{L}}^{-1}{\min }^{-1}, \frac{∆\left[{\mathrm{Br}}_2\right]}{∆\mathrm{t}}\mathrm{in} \mathrm{mol} {\mathrm{L}}^{-1}{\min }^{-1}\mathrm{is}$

• 0.01

• 0.3

• 0.03

• 0.005

The half-life of Th²³² is 1.4 × 10¹⁰ years and that of its daughter element Ra²³⁸ is 7 years. What amount (most nearly) weight of Ra²³⁸ will be in equilibrium with 1 gm of Th²³²?

• 5.0 gm

• 1.95 × 10^-9 gm

• 2 × 10^-10 gm

• 5 × 10^-10 gm

Which of the following are the correct representations of a zero order reaction, where A represents the reactant?

• I, II, III

• I, II, IV

• II, III, IV

• 1, III, II

Which of the following statement(s) is/are true

• The pressure of a fixed amount of an ideal gas is proportional to its temperature only

• Frequency of collision increases in proportion to the square root of temperature

• The value of van der Waal's constant'a' is smaller for ammonia than for nitrogen

• If a gas is expanded at constant temperature, the kinetic energy of the molecules decrease

For the reaction 2A + B → C, the values of initial rate at different reactant concentrations are given in the table below. The rate law for the reaction is :

[A] (mol L-1)	[B] (mol L-1)	Initial rate (mol L-1 s-1)
0.05	0.05	0.045
0.10	0.05	0.090
0.20	0.10	0.72

• Rate = k[A]²[B]²

• Rate = k[A]²[B]

• Rate = k[A][B]

• Rate = k[A][B]²

For a reaction scheme A $\stackrel{{\mathrm{k}}_1}{\to } \mathrm{B} \stackrel{{\mathrm{k}}_2}{\to }\mathrm{C}$, if the rate of formation of B is set to be zero then the concentration of B is given by:

• (k₁ + k₂)[A]

• (k₁ - k₂)[A]

• $\left(\frac{{\mathrm{k}}_1}{{\mathrm{k}}_2}\right)\left[\mathrm{A}\right]$

• k₁k₂[A]