Automotive Engine Auxiliary Systems Questions and Answers – Lead-Acid Battery

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This set of Automotive Engine Auxiliary Systems Multiple Choice Questions & Answers (MCQs) focuses on “”.

1. What is the percentage of acid and water present in the electrolyte of a lead-acid battery in a fully charged condition?
a) 39% acid and 61% water
b) 45% acid and 65% water
c) 30% acid and 70% water
d) 25% acid and 75% water
View Answer

Answer: a
Explanation: The electrolyte in a lead-acid battery contains 39 percentage of acid and 61 percentage of water in a fully charged condition. Whereas in the fully discharged condition it contains 85 percentage of water and 15 percentage of acid.
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2. Which of the following is the electrolyte used in a lead-acid battery?
a) Nitric acid
b) Sulphuric acid
c) Lead-acid
d) Hydrochloric acid
View Answer

Answer: b
Explanation: The battery is filled with electrolyte. The electrolyte used in the lead-acid battery is a solution of sulphuric acid. It contains approximately one part of sulphuric acid to two part of water by volume. It should be noted that acid should be added to water and not the vice versa.

3. Which is the active material present on the negative plate in a lead-acid battery?
a) Lead dioxide
b) Lead peroxide
c) Spongy lead
d) Water
View Answer

Answer: c
Explanation: The positive and negative electrodes of a lead-acid battery are immersed in dilute sulphuric acid. On the positive plate, we have lead peroxide and on the negative plate, the active material is spongy lead.
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4. What is the total number of cells present in a 12-volt battery?
a) 5
b) 6
c) 3
d) 4
View Answer

Answer: b
Explanation: A 12-volt battery consists of six cells connected in series wherein each cell provides 2 volts. One positive and one negative group of plates are sliding over each other. The size of the plates and their number per cell determine the capacity of the battery.

5. Which of the following energy is converted to electricity by the battery?
a) Mechanical energy
b) Chemical energy
c) Thermal energy
d) Electrical energy
View Answer

Answer: b
Explanation: A battery is a device for storing chemical energy and converting the same into electricity. It supplies current to operate the lighting and various accessories, when the engine is not running, for the starting of the vehicle as well as to ignition system.
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6. Which of the following is the material used for separator?
a) Nickel
b) Cast iron
c) Ebonite
d) Bronze
View Answer

Answer: c
Explanation: To avoid direct contact and thus short-circuiting of positive and negative plates, thin sheets of some no conducting material are inserted between them. These sheets are called as separators. These are made from ebonite, porous rubber, fibreglass etc.

7. What is the correct count of negative plates with respect to positive plates in a battery?
a) Both positive and negative have the same number of plates
b) More positive plates when compared to negative plates
c) More negative plates when compared to positive plates
d) Have no relation between them
View Answer

Answer: c
Explanation: One positive and one negative group of plates are slid over each other, with separators in between, to form a cell. Most batteries have one more negative plate than positive plates in each cell. The size of plates and their number per cell determine the capacity of the battery.
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8. Which of the following material is used in the positive plate of a lead-acid battery?
a) Sulphuric acid
b) Spongy lead
c) Lead peroxide
d) Water
View Answer

Answer: c
Explanation: When the battery is fully charged there is lead peroxide on the positive plate and lead spongy on the negative plate as an active material. During the process of discharge, the chemical reactions forms lead sulphate on both the plates thereby liberating water.

9. Which of the following increase due to which the electrode gravity decreases?
a) Enthalpy
b) Entropy
c) Temperature
d) Pressure
View Answer

Answer: c
Explanation: The electrolyte gravity varies with temperature. It increases with the decrease in temperature and vice versa. The gravity value is always mentioned at a specified standard temperature, which is usually 15-degree centigrade.
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10. What is the amount of water and acid present in the electrolyte after the full discharge of the battery?
a) 90% of water and 10% of acid
b) 85% of water and 15% of acid
c) 70% of water and 30% of acid
d) 75% of water and 25% of acid
View Answer

Answer: b
Explanation: The ratio of water and acid in the full discharged state is 85 per cent of water and 15 percentage of acid whereas in the fully charged condition the electrolyte contains 39 percentage of acid and 61 percentage of water.

11. Which among the following colour is used to indicate the positive terminal of the battery?
a) Blue
b) Green
c) Black
d) Red
View Answer

Answer: d
Explanation: The positive terminal of the battery is coated with red colour and the negative terminal is coated with black colour. During the removal of the battery first, remove the negative terminal and then the positive terminal.

12. Due to which of the following the separator is made porous?
a) To dissipate heat
b) Increases efficiency
c) Allow the diffusion of acid
d) Acts as a pressure relief
View Answer

Answer: c
Explanation: The material of the separator, apart from being non conducting, must be sufficiently porous or perforated to allow diffusion of the acid. The separator must be slightly thinner than space into which they fit.

13. Which of the following component is formed on the positive plate after the discharged reaction in a lead-acid battery?
a) Sulphuric acid
b) Lead peroxide
c) Lead sulphate
d) Spongy lead
View Answer

Answer: c
Explanation: During the process of discharge the chemical reactions forms lead sulphate on both the positive and negative plate thereby liberating water. The specific gravity of the electrolyte is lowered. The specific gravity is a good indication of the state of charge of a battery.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn | Youtube | Instagram | Facebook | Twitter