From (3), K is the middle term.

___ ___ ___ _K_ ___ ___ ___

From (4), there must be exactly 2 numbers between J and M which gives two possible positions.

[1] ___ _M_ ___ _K_ _J_ ___ ___

[2] ___ ___ _M_ _K_ ___ _J_ ___

From (1), the number of letters between O and K must be same as the number of letters between M and L. Also, the number of letters between them can be 1, 2 or 3. Using trial and error, it can be found that there must be 2 letters between them. Also, it is possible only in option [2] above.

[2] ___ _O_ _M_ _K_ _L_ _J_ ___

From (2) Z must be the highest and the remaining N must be the lowest number.

_N_ _O_ _M_ _K_ _L_ _J_ _Z_Thus, the sequence of letters from the lowest value to the highest value is NOMKLJZ.