MCQ Detailed View

The lead-acid battery, also known as the lead storage battery, is one of the oldest and most widely used rechargeable batteries. It is classified as a secondary battery, meaning it can be recharged after use. The battery is commonly used in automobiles, inverters, and backup power systems due to its reliability and cost-effectiveness.

In a lead-acid battery, two different plates are used as electrodes: the positive plate is coated with lead dioxide (PbO₂) paste, while the negative plate is made of spongy lead (Pb). These plates are immersed in a sulfuric acid (H₂SO₄) solution, which acts as the electrolyte. The paste of lead dioxide is crucial because it provides a high surface area for the chemical reactions and allows efficient electron transfer.

During discharge, the PbO₂ paste on the positive plate reacts with sulfuric acid and converts into lead sulfate (PbSO₄), while the spongy lead on the negative plate also forms PbSO₄. This reaction releases electrons, which flow through an external circuit, providing electrical energy. When the battery is recharged, the reaction reverses, regenerating PbO₂ on the positive plate and spongy Pb on the negative plate, while restoring the concentration of sulfuric acid.

The choice of PbO₂ paste is critical for battery efficiency. Other substances like manganese dioxide, zinc chloride, or ammonium chloride are used in dry cells or other types of batteries but not in lead-acid batteries. The PbO₂ paste provides stability, high energy density, and the ability to undergo repeated charging cycles.

Key facts:

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  Lead-acid battery is a secondary (rechargeable) battery.

  
  


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  Positive plate → Lead dioxide (PbO₂) paste.

  
  


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  Negative plate → Spongy lead (Pb).

  
  


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  Electrolyte → Sulfuric acid (H₂SO₄).

  
  


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  Commonly used in cars, UPS, and inverters.

  
  

Thus, the paste used in a lead battery is Lead oxide paste (PbO₂).