Are condoms a hundred percent effective against gonorrhea?

No. Condoms are never 100% effective to prevent stds due to failure (breakage for example) that may occur. Your best bet is safe and responsible intercourse with a partner with known sexual history. Abstinence is the only 100% effective method to prevent stds.
No. Condoms are not 100% effective in the prevention of any disease. Condoms sometimes fail. People sometimes put on condoms too late. Gonorrhea germs can also be transmitted by one's hands and fingers (if they get contaminated during sexual activity), and by one's mouth if he or she has mouth or throat gonorrhea.