Is this true ? sperm without liquid seminal is dead . this means that if a hand had sperm and dried because nothing is visible on them after 5 min. this means sperm is dead so no pregnancy ?

That is correct, pregnancy is not possible in above circumstances. Contraception remains otherwise key in avoiding undesired pregnancy and associated anxiety, specifically when intercourse becomes possible.

Dry semen does not have viable sperm in it. Get HPV vaccine. Wish you good health! Safe sex: https://www.hopkinsmedicine.org/health/wellness-and-prevention/safer-sex-guidelines