Which of the following penicillins is given by oral route?
Oral Administration of Penicillin G and V

The virtue of penicillin V in comparison with penicillin G is that it is more stable in an acidic medium and therefore is better absorbed from the GI tract, yielding plasma concentrations two to five times those provided by penicillin G. 
Thus, penicillin V is generally preferred for oral administration. 
Absorption is rapid, and maximal concentrations in blood are attained in 30–60 min.
 Ingestion of food may interfere with enteric absorption of all penicillins. Thus, oral penicillins should generally be administered at least 30 min before a meal or 2 hr after.

Reference: Goodman & Gilman’s THE PHARMACOLOGICAL BASIS OF THERAPEUTICS THIRTEENTH EDITION
Page no 1026
Benzyl penicillin
Benzathine penicillin
Procaine penicillin
Penicillin V / Phenoxymethyl penicillin