There are five boys Prem, Raju, Sundar, Hari and Ompal. Raju has more share of land than Sundar but lesser than Prem. Ompal has the least share and Hari has lesser share of land than Sundar. Who owns the highest share of land?

Let us translate the inequalities from the problem statement:
"Raju has more share of land than Sundar but lesser than Prem":

Prem>Raju>Sundar
"Ompal has the least share":

Ompal is at the bottom end.
"Hari has lesser share of land than Sundar":

Sundar>Hari
Combining all the derived conditions together:

Prem>Raju>Sundar>Hari>Ompal
Therefore, Prem owns the highest share of land.