Equation A:
3H2SO4+2AL ---> AL2(SO4)3+3H2
For the reactants we have:
6 moles of hydrogen
3 moles of sulphur
12 moles of oxygen
2 moles of aluminum
For the products we have:
2 moles of aluminum
3 moles of sulphur
12 moles of oxygen
6 moles of hydrogen
Comparing the number of moles of each element in the reactants and products side of the equation, we can see that this equation is balanced
Equation B:
2KCL+Pb(NO3)2 ---> KNO3 +PbCl2
For the reactants we have:
2 moles of K
2 moles of Cl
1 mole of Pb
2 moles of N
6 moles of O
For the products we have:
1 mole of K
1 mole of N
3 moles of O
1 mole of Pb
2 moles of Cl
Comparing the number of moles of each element in the reactants and products side of the equation, we will find that K,N and O are not balanced.
Therefore, this equation is not balanced.