Rankbit System
JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%) | JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%)

The mass of zinc produced by the electrolysis of zinc sulphate solution with a steady current of 0.015 A for 15 minutes is \_\_\_\_\_\_ times 10^-4 g. (Atomic mass of zinc = 65.4 amu)

Numerical Answer Type:
Enter a numerical value Answer: 45.75 to 46 +4 marks

Solution & Explanation

### Related Formula W = Z cdot I cdot t = fracMn cdot F cdot I cdot t where, W = mass deposited Z = electrochemical equivalent I = current in amperes t = time in seconds M = molar mass n = n-factor (electrons exchanged) F = Faraday's constant (96500 text C/mol) ### Core Logic The electrolysis of zinc sulphate (ZnSO_4) involves the reduction of zinc ions at the cathode: Zn^+2 + 2e^- rightarrow Zn Here, the n-factor (n) is 2. ### Step 1: Calculation Given values: I = 0.015text A t = 15text minutes = 15 times 60text seconds = 900text s M = 65.4text g/mol F approx 96500text C Plugging the values into Faraday's First Law: W = frac65.42 times 96500 times 0.015 times 15 times 60 W = frac65.4193000 times 13.5 W = 3.3886 times 10^-4 times 13.5 W = 45.746 times 10^-4text g Rounding to two decimal places (or nearest integer depending on convention), we get 45.75 times 10^-4text g. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Chemistry: Electrochemistry

Reference Study Guides

More Electrochemistry Previous-Year Questions — Page 5

Q89 jee_main_2024_29_january_evening Faraday's Laws of Electrolysis
A constant current was passed through a solution of mathrmAuCl_4^- ion between gold electrodes. After a period of 10.0 minutes, the increase in mass of cathode was 1.314mathrmg. The total charge passed through the solution is ________ times 10^-2mathrmF. (Given atomic mass of mathrmAu = 197)
Numerical Answer. Answer: 2 to 2

Solution

### Related Formula textNumber of equivalents deposited = fracW, E = fracQ, F textEquivalent Weight (E) = fractextAtomic Mass, ntext-factor ### Core Logic In the reduction of gold from the tetrachloroaurate(III) complex anion: mathrmAuCl_4^- + 3e^- rightarrow mathrmAu(s) + 4mathrmCl^- implies ntext-factor = 3 Calculate the equivalent weight (E) of Gold: E = frac197, 3 Set up the Faraday equivalence relation to solve for charge (Q in Faradays): frac1.314, left(frac197, 3right) = Q ### Step 1: Arithmetic Resolution Q = frac1.314 times 3, 197 = frac3.942, 197 = 0.02text F = 2 times 10^-2text F Thus, the required integer value is **2**. ### Pattern Recognition Always determine the correct change in oxidation state (+3 to 0) to establish the proper n-factor value for calculations using Faraday's laws. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Chemistry: Electrochemistry
Q81 jee_main_2024_27_jan_morning Faraday's Laws of Electrolysis
The mass of silver (Molar mass of textAg: 108text g mol^-1) displaced by a quantity of electricity which displaces 5600text mL of O_2 at S.T.P. will be textquadquad g.
Numerical Answer. Answer: 107 to 108

Solution

### Related Formula By Faraday's Second Law of Electrolysis: textEquivalents of Ag = textEquivalents of O_2 textEquivalents = fractextMasstextEquivalent Mass = textMoles times ntext-factor ### Step 1: Calculate equivalents using standard metrics Let x grams of Silver be displaced. Using the older STP molar volume baseline (22.4text L or 22400text mL): textMoles of O_2 = frac560022400 = 0.25text moles Since the n-factor of O_2 is 4 (2textO^2- rightarrow textO_2 + 4texte^-): textEquivalents of O_2 = 0.25 times 4 = 1 ### Step 2: Equating equivalents for silver mass textEquivalents of Ag = fracx108 times 1 = 1 implies x = 108text g ### Step 3: Alternative calculation using current STP metric Using modern STP volume metrics (22.7text L): fracx times 1108 = frac5.622.7 times 4 implies x approx 106.57text g rightarrow 107text g ### Pattern Recognition Equivalents equations bypass complex current/time measurements. Always link volume fractions directly to n-factor equivalents. ### Chapter Mix Class 12 Chemistry: Electrochemistry Class 11 Chemistry: Some Basic Concepts of Chemistry
Q80 jee_main_2024_30_january_evening Standard Electrode Potential
Reduction potential of ions are given below: mathrmClO_4^- quad E^circ = 1.19mathrmV mathrmIO_4^- quad E^circ = 1.65mathrmV mathrmBrO_4^- quad E^circ = 1.74mathrmV The correct order of their oxidising power is:
  • A. mathrmClO_4^- > mathrmIO_4^- > mathrmBrO_4^-
  • B. mathrmBrO_4^- > mathrmIO_4^- > mathrmClO_4^-
  • C. mathrmBrO_4^- > mathrmClO_4^- > mathrmIO_4^-
  • D. mathrmIO_4^- > mathrmBrO_4^- > mathrmClO_4^-

Solution

### Core Logic The Standard Reduction Potential (E^circ) measures a species' tendency to undergo reduction (gain electrons). A higher, more positive E^circ value means the species has a stronger tendency to be reduced, which in turn makes it a stronger oxidizing agent. Comparing the given E^circ values: mathrmBrO_4^-: 1.74mathrmV mathrmIO_4^-: 1.65mathrmV mathrmClO_4^-: 1.19mathrmV The order of oxidizing power follows the magnitude of the reduction potential: mathrmBrO_4^- > mathrmIO_4^- > mathrmClO_4^- ### Pattern Recognition Higher +ve Standard Reduction Potential (SRP) = Stronger Oxidising Agent. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Chemistry: Electrochemistry Class 12 Chemistry: The p Block Elements
Q65 jee_main_2024_31_jan_morning Batteries
The metals that are employed in the battery industries are A. Fe B. Mn C. Ni D. Cr E. Cd Choose the correct answer from the options given below:
  • A. textB, C and E only
  • B. textA, B, C, D and E
  • C. textA, B, C and D only
  • D. textB, D and E only

Solution

### Core Logic Mn, Ni, and Cd metals are predominantly used in battery industries. - Mn is used in dry cells (Leclanche cell). - Ni and Cd are used in Nickel-Cadmium (Ni-Cd) rechargeable batteries. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Chemistry: Electrochemistry

More Electrochemistry Questions — jee_main_2024_29_jan_morning

Practice all Electrochemistry previous-year questions →

YOUR FIRST PREP STEP STARTS HERE

We Map Every Repeating Question in Competitive Exams.

Say goodbye to generic mock test fatigue. RankBit uses smart analysis to group past exam questions into their foundational Repeating Question Types. Find chapter weightage, track repeating questions, and score higher with targeted practice.

Select Your Target Exam

Choose an exam track below to find formulas per chapter and patterns.

Syncing Exam Intelligence

Mapping formulas and patterns across all tracks…

PATH A — FULL LENGTH PRACTICE

Full Mock Test Hub

Simulate real NTA exam conditions with fully tracked mocks. Time yourself against past papers.

Under Development
PATH B — TARGETED PRACTICE

Topic-wise Practice Hub

Practice past-year questions one chapter at a time. Pick an exam → subject → chapter and get every PYQ for that topic — pulled together from all past papers — with the chapter's key formulas alongside.

Loading Questions... Browse Topics
Latest from the Blog
View all →

Loading articles...