The order of magnitude of a physical quantity is its magnitude in powers of ten when the physical quantity is expressed in powers of ten with one digit to the left of the decimal.

Orders of magnitude are generally used to make very approximate comparisons and reflect very large differences.

SinceECu2+/CuECu2+/Cuhas a greater positive value thanEH+/HEH+/H, the reaction that is feasible at the cathode is

Cu2+(aq)+2eCu(s)

zinc will react with sulphuric acid forming zinc sulphate dissolved in solution and releasing hydrogen gas.
Zn + conc. 2 H2SO4 ZnSO4 + SO2 + 2 H2O