8. While charging the lead storage battery . [NCERT Exemplar] (a) PbSO4 anode is reduced to Pb. (b) PbSO4 cathode is reduced to Pb. (c) PbSO4 cathode is oxidised to Pb. (d) PbSO4 anode is oxidised to PbO2.

PbO2 is formed at the anode from PbSO4

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"