1
JEE Main 2021 (Online) 24th February Evening Shift
Numerical
+4
-1
Sucrose hydrolyses in acid solution into glucose and fructose following first order rate law with a half-life of 3.33 h at 25$$^\circ$$C. After 9 h, the fraction of sucrose remaining is f. The value of $${\log _{10}}\left( {{1 \over f}} \right)$$ is ________ $$\times$$ 10$$-$$2. (Rounded off to the nearest integer)

[Assume : ln 10 = 2.303, ln 2 = 0.693]
2
JEE Main 2021 (Online) 24th February Morning Shift
Numerical
+4
-1
Gaseous cyclobutene isomerises to butadiene in a first order process which has a 'k' value of 3.3 $$\times$$ 10-4 s-1 at 153°C. The time in minutes it takes for the isomerization to proceed 40% to completion at this temperature is ______.
(Rounded off to the nearest integer)
3
JEE Main 2020 (Online) 6th September Evening Slot
Numerical
+4
-0
The rate of a reaction decreased by 3.555 times when the temperature was changed from 40oC to 30oC. The activation energy (in kJ mol–1) of the reaction is _______.

Take; R = 8.314 J mol–1 K–1 ln 3.555 = 1.268
4
JEE Main 2020 (Online) 4th September Evening Slot
Numerical
+4
-0
The number of molecules with energy greater than the threshold energy for a reaction increases five fold by a rise of temperature from 27oC to 42oC. Its energy of activation in J/mol is _____.
(Take ln 5 = 1.6094; R = 8.314 J mol–1 K–1)