1
JEE Main 2023 (Online) 1st February Morning Shift
Numerical
+4
-1
Change Language

A and B are two substances undergoing radioactive decay in a container. The half life of A is 15 min and that of B is 5 min. If the initial concentration of B is 4 times that of A and they both start decaying at the same time, how much time will it take for the concentration of both of them to be same? _____________ min.

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2
JEE Main 2023 (Online) 31st January Evening Shift
Numerical
+4
-1
Change Language
The rate constant for a first order reaction is $20 \mathrm{~min}^{-1}$. The time required for the initial concentration of the reactant to reduce to its $\frac{1}{32}$ level is _______ $\times 10^{-2} \mathrm{~min}$. (Nearest integer)

(Given : $\ln 10=2.303$ and $$ \log 2=0.3010 \text { )}$$
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3
JEE Main 2023 (Online) 31st January Morning Shift
Numerical
+4
-1
Change Language

A $$\to$$ B

The rate constants of the above reaction at 200 K and 300 K are 0.03 min$$^{-1}$$ and 0.05 min$$^{-1}$$ respectively. The activation energy for the reaction is ___________ J (Nearest integer)

(Given : $$\mathrm{ln10=2.3}$$

$$\mathrm{R=8.3~J~K^{-1}~mol^{-1}}$$

$$\mathrm{\log5=0.70}$$

$$\mathrm{\log3=0.48}$$

$$\mathrm{\log2=0.30}$$)

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4
JEE Main 2023 (Online) 30th January Evening Shift
Numerical
+4
-1
Change Language
An organic compound undergoes first-order decomposition. If the time taken for the $60 \%$ decomposition is $540 \mathrm{~s}$, then the time required for $90 \%$ decomposition will be ________ s. (Nearest integer).

Given: $\ln 10=2.3 ; \log 2=0.3$
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