Is Alan Alda old enough to have fought in the Vietnam War?
Alan Alda was born in 1936. The Vietnam War was from 1955 to 1975, with American involvement from 1965 to 1973. American soldiers must be at least 18 years old. Alan Alda was 29 in 1965.
The answer is yes.

Can eating your weight in celery prevent diabetes?
Diabetes is a disease in which the body cannot process sugar. Celery is known as a healthy snack and has 1 gram of sugar per serving. The recommended daily intake of sugar to prevent diabetes is less than 36 grams per day for an adult male. The average weight of an adult male is 197 pounds.
The answer is no.

Does Rupert Murdoch's alma mater have more history than the USA?
Rupert Murdoch's alma mater is Worcester College. Worcester College was founded in 1714. The first documented use of the term the United States of America was in a January 2, 1776 letter.
The answer is yes.

Did Jack Dempsey fight the current WBC heavyweight champion?
Jack Dempsey died in 1983. The current WBC heavyweight champion is Tyson Fury. Tyson Fury was born in 1988.
The answer is no.