A H-atom moving with speed v makes a head on collision with a H-atom in rest. Both atoms are in ground state. Find the minimum value of velocity v for which one of atom may excite.
A. `6.25xx10^(4)ms^(-1)`
B. `8xx10^(4)ms^(-1)`
C. `7.25xx10^(4)ms^(-1)`
D. `13.6xx10^(4)ms^(-1)`