1
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)
2
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)
3
JEE Main 2020 (Online) 3rd September Evening Slot
Numerical
+4
-0
An acidic solution of dichromate is electrolyzed for 8 minutes using 2A current. As per the following equation
Cr2O72- + 14H+ + 6e $$\to$$ 2Cr3+ + 7H2O
The amount of Cr3+ obtained was 0.104 g. The efficiency of the process(in%) is (Take : F = 96000 C, At. mass of chromium = 52) ______.
4
JEE Main 2020 (Online) 3rd September Morning Slot
Numerical
+4
-0
The photoelectric current from Na (Work function, w0 = 2.3 eV) is stopped by the output voltage of the cell
Pt(s) | H2 (g, 1 Bar) | HCl (aq., pH =1) | AgCl(s) | Ag(s).
The pH of aq. HCl required to stop the photoelectric current form K(w0 = 2.25 eV), all other conditions remaining the same, is _______ $$\times$$ 10-2 (to the nearest integer).

Given, 2.303$${{RT} \over F}$$ = 0.06 V;
$$E_{AgCl|Ag|C{l^ - }}^0$$ = 0.22 V