What happens to lead acid’s electrolyte’s specific gravity while charging?

This question was previously asked in
ALP CBT 2 Electrician Previous Paper: Held on 23 Jan 2019 Shift 2
View all RRB ALP Papers >
  1. It increases
  2. It remains the same
  3. It evaporates
  4. It decreases

Answer (Detailed Solution Below)

Option 1 : It increases
Free
General Science for All Railway Exams Mock Test
20 Qs. 20 Marks 15 Mins

Detailed Solution

Download Solution PDF
  • The electrolyte in a lead-acid cell is dilute sulphuric acid (H2SO4) solution mixed in such a proportion so that with a fully charged battery, its specific gravity is about 1.28
  • Dilute sulphuric acid is used as electrolyte by adding Sulphuric acid to water
  • Spongy lead is used for negative plate
  • Lead peroxide paste is used for positive plates
  • It has low internal resistance
  • It requires more charging time
  • Gases are evolved during charging
  • During the normal life of a battery that is properly cared for, the electrolyte loses none of the acids
  • During the charging process, the specific gravity of the electrolyte (H2SO4) increases and provides an important indication to the state of charge of the cell
  • The specific gravity of the electrolyte of a fully charged lead-acid cell is about 1.28; This can be measured by means of a hydrometer
  •  

    In practice, the state of charge of a lead-acid cell (or battery) is determined from the specific gravity of the electrolyte. The following table is useful in this regard.

    The specific gravity of H2SO4

    State of charge

    1.13

    Discharged

    1.19

    25% charged

    1.22

    50% charged

    1.25

    75% charged

    1.28

    100% charged

Latest RRB ALP Updates

Last updated on Jul 15, 2025

-> The Railway Recruitment Board has scheduled the RRB ALP Computer-based exam for 15th July 2025. Candidates can check out the Exam schedule PDF in the article.

-> RRB has also postponed the examination of the RRB ALP CBAT Exam of Ranchi (Venue Code 33998 – iCube Digital Zone, Ranchi) due to some technical issues.

-> The Railway Recruitment Board (RRB) has released the official RRB ALP Notification 2025 to fill 9,970 Assistant Loco Pilot posts.

-> The official RRB ALP Recruitment 2025 provides an overview of the vacancy, exam date, selection process, eligibility criteria and many more.

->The candidates must have passed 10th with ITI or Diploma to be eligible for this post. 

->The RRB Assistant Loco Pilot selection process comprises CBT I, CBT II, Computer Based Aptitude Test (CBAT), Document Verification, and Medical Examination.

-> This year, lakhs of aspiring candidates will take part in the recruitment process for this opportunity in Indian Railways. 

-> Serious aspirants should prepare for the exam with RRB ALP Previous Year Papers.

-> Attempt RRB ALP GK & Reasoning Free Mock Tests and RRB ALP Current Affairs Free Mock Tests here

Hot Links: online teen patti teen patti master old version teen patti - 3patti cards game