1
JEE Main 2021 (Online) 27th July Evening Shift
Numerical
+4
-1
For the first order reaction A $$\to$$ 2B, 1 mole of reactant A gives 0.2 moles of B after 100 minutes. The half life of the reaction is __________ min. (Round off to the nearest integer).

[Use : ln 2 = 0.69, ln 10 = 2.3]

Properties of logarithms : ln xy = y ln x;

$$\ln \left( {{x \over y}} \right) = \ln x - \ln y$$

(Round off to the nearest integer)
2
JEE Main 2021 (Online) 25th July Evening Shift
Numerical
+4
-1
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)
3
JEE Main 2021 (Online) 22th July Evening Shift
Numerical
+4
-1
$${N_2}{O_{5(g)}} \to 2N{O_{2(g)}} + {1 \over 2}{O_{2(g)}}$$

In the above first order reaction the initial concentration of N2O5 is 2.40 $$\times$$ 10$$-$$2 mol L$$-$$1 at 318 K. The concentration of N2O5 after 1 hour was 1.60 $$\times$$ 10$$-$$2 mol L$$-$$1. The rate constant of the reaction at 318 K is ______________ $$\times$$ 10$$-$$3 min$$-$$1. (Nearest integer)

[Given : log 3 = 0.477, log 5 = 0.699]
4
JEE Main 2021 (Online) 20th July Evening Shift
Numerical
+4
-1
$$PC{l_5}(g) \to PC{l_3}(g) + C{l_2}(g)$$

In the above first order reaction the concentration of PCl5 reduces from initial concentration 50 mol L$$-$$1 to 10 mol L$$-$$1 in 120 minutes at 300 K. The rate constant for the reaction at 300 K is x $$\times$$ 10$$-$$2 min$$-$$1. The value of x is __________. [Given log5 = 0.6989]