The metal commonly used in storage batteries ____?

The metal commonly used in storage batteries ____?

اسٹوریج بیٹریوں میں عام طور پر استعمال ہونے والی دھات _______؟
Explanation

A lead-acid battery consists of a negative electrode made of spongy or porous lead.

The lead is porous to facilitate the formation and dissolution of lead.