Blue vitriol is chemically :

Explanation

## Page 33 A secondary cell is used in cars. In a secondary cell, a dilute solution of sulphuric acid is used as the electrolyte, while the electrodes are plates made of lead dioxide (PbO₂) and spongy lead. These batteries are also called lead accumulators or storage batteries. Batteries used in cars, trucks, and inverters are examples of secondary batteries.