The electrical expenditure is two rupees to produce one gram of calcium from fused `CaSO_4`. What is the production cost of 2 grams of hydrogen produced electrically from acidulated water?

Explanation

`Ca^(2+) (aq) + 2e^(-) to Ca(s) and 2H^(+)(aq) + 2e^(-) to H_2(g)`
2 Faradays are required to deposit 40 g of Ca or to liberate 2 g of hydrogen.
Cost incurred in producing 2g of hydrogen = `(40 g)/(1g) xx 2 = 80` rupees.