Learn

Saturday, 31 October

JEE Main 2020 · ChemistryNumerical answerNumerical valueHardMulti-step

JEE Main 3 September 2020, Shift 1, Chemistry Q48

Question 48 of 75 in this shift, Chemistry question 23 of 25.

The photoelectric current from Na (work function, w0=2.3\mathrm{w_0}=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)\mathrm{Pt(s)|H_2(g,\ 1\ bar)|HCl(aq.,\ pH=1)|AgCl(s)|Ag(s)}. The pH of aq. HCl required to stop the photoelectric current from K(w0=2.25\mathrm{w_0}=2.25 eV), all other conditions remaining the same, is __________ ×10−2\times10^{-2} (to the nearest integer). Given, 2.303 RTF=0.062.303\,\dfrac{\mathrm{RT}}{\mathrm{F}}=0.06 V; EAgCl∣Ag∣Cl−0=0.22\mathrm{E^0_{AgCl|Ag|Cl^-}}=0.22 V

Official answer

58.00

NTA final key (Sep 2020).

Chapter
Electrochemistry
Topic
Nernst Equation
Idea tested
Full Cell Nernst Equation

Same idea in other shifts

Asked 12× in all
  1. 4 Apr 2026, Shift 2 · Q73An electrochemical cell, consist of the following two redox couples, Mx+(aq)/M(s)\mathrm{M^{x+}(aq)/M(s)} [Ered⊖=+0.15 V][E^\ominus_{red}=+0.15\ \mathrm{V}] and…HardNumerical value
  2. 5 Apr 2026, Shift 2 · Q57One half cell in a voltaic cell is constructed by dipping silver rod in AgNO3\mathrm{AgNO_3} solution of unknown concentration, other half…MediumSingle correct
  3. 7 Apr 2025, Shift 1 · Q711 Faraday electricity was passed through Cu2+\mathrm{Cu^{2+}} (1.5 M, 1 L) /Cu and 0.1 Faraday was passed through Ag+\mathrm{Ag^+} (0.2 M, 1…HardNumerical valueHas a figure
  4. 8 Apr 2024, Shift 2 · Q63The emf of cell Tl ∣ Tl+(0.001 M) ∣∣ Cu2+(0.01 M) ∣ Cu\mathrm{Tl\,|\,Tl^+(0.001\,M)\,||\,Cu^{2+}(0.01\,M)\,|\,Cu} is 0.83 V at 298 K. It could be increased by :MediumSingle correct
  5. 25 Jul 2022, Shift 1 · Q84The cell potential for Zn∣Zn2+(aq)∥Snx+∣ Sn\mathrm{Zn|Zn^{2+}(aq)\|Sn^{x+}|\,Sn} is 0.8010.801 V at 298 K. The reaction quotient for the above reaction is…MediumNumerical value
  6. 29 Jul 2022, Shift 2 · Q84For a cell, Cu(s)∣Cu2+(0.001M)∣∣Ag+(0.01M)∣Ag(s)\mathrm{Cu(s) \mid Cu^{2+}(0.001M) \mid\mid Ag^{+}(0.01M) \mid Ag(s)} the cell potential is found to be 0.43 V at 298 K. The…MediumNumerical value
  7. 24 Jun 2022, Shift 1 · Q84The cell potential for the following cell Pt ∣H2(g)∣H+(aq)∥ Cu2+(0.01 M)∣Cu(s)\mathrm{Pt\,|H_2(g)|H^+(aq)\|\ Cu^{2+}(0.01\ M)|Cu(s)} is 0.576 V at 298 K. The pH of the…MediumNumerical value
  8. 26 Aug 2021, Shift 2 · Q56For the galvanic cell, Zn(s)+Cu2+\mathrm{Zn(s) + Cu^{2+}} (0.02 M) →Zn2+\rightarrow \mathrm{Zn^{2+}} (0.04 M) +Cu(s)+ \mathrm{Cu(s)}, Ecell\mathrm{E_{cell}}…MediumNumerical value

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.