Question

Which of these equations is balanced?

Answer 1

Both are already balanced. So, your answer would be: C. a and b

Answer 2

To calculate your answer: 
list atoms
multiply by subcript outside parentheses
multiply by coefficient

3 H2SO4 + 2Al → Al2(SO4)3 + 3H2

H  2  x3 =6                  H 2 x 3 = 6
S  1 x 3 = 3                 S 1x 3 = 3
O  4  x3 = 12              O 4 x 3 = 12
Al  1  x 2 = 2               Al 2


This one is balanced . . . now you try the other one.  Let me know if you still need help