1
JEE Main 2021 (Online) 25th February Evening Shift
Numerical
+4
-1
Copper reduces NO$$_3^ -$$ into NO and NO2 depending upon the concentration of HNO3 in solution. (Assuming fixed [Cu2+] and PNO = PNO2), the HNO3 concentration at which the thermodynamic tendency for reduction of NO$$_3^ -$$ into NO and NO2 by copper is same is 10x M. The value of 2x is _______. (Rounded off to the nearest integer)

[Given, $$E_{C{u^{2 + }}/Cu}^o = 0.34$$ V, $$E_{NO_3^ - /NO}^o = 0.96$$ V, $$E_{NO_3^ - /N{O_2}}^o = 0.79$$ V and at 298 K, $${{RT} \over F}$$(2.303) = 0.059]
2
JEE Main 2021 (Online) 24th February Evening Shift
Numerical
+4
-1
The magnitude of the change in oxidising power of the $$MnO_4^ - /M{n^{2 + }}$$ couple is x $$\times$$ 10$$-$$4 V, if the H+ concentration is decreased from 1M to 10$$-$$4 M at 25$$^\circ$$C. (Assume concentration of $$MnO_4^ -$$ and $$M{n^{2 + }}$$ to be same on change in H+ concentration). The value of x is ___________. $$\left[ {Given\,:{{2.303RT} \over F} = 0.059} \right]$$
3
JEE Main 2020 (Online) 6th September Morning Slot
Numerical
+4
-0
Potassium chlorate is prepared by the electrolysis of KCl in basic solution

6OH- + Cl- $$\to$$ ClO3- + 3H2O + 6e-

If only 60% of the current is utilized in the reaction, the time (rounded to the nearest hour) required to produce 10 g of KClO3 using a current of 2 A is_________.

(Given : F = 96,500 C mol–1; molar mass of KCIO3 = 122 g mol–1)
4
JEE Main 2020 (Online) 5th September Morning Slot
Numerical
+4
-0
An oxidation-reduction reaction in which
3 electrons are transferred has a $$\Delta$$Gº of 17.37 kJ mol–1 at
25 oC. The value of Eo
cell (in V) is ______ × 10–2.
(1 F = 96,500 C mol–1)