Would a pregnancy test be accurate 25 days after intercourse ?

It depends...: Home birth control tests are about 99% accurate if it has been one week since a period was missed. They may detect a pregnancy earlier than that but are less reliable. So the number of days after intercourse is less important than the number of days since the missed period as far as test accuracy is concerned.

Most probably: Most home urine pregnancy tests should be fairly "accurate 28 days after intercourse" and have a very low probability of false positive or false negative results if these tests are performed properly according to their manufacturers. The urine pregnancy tests and the blood beta HCG tests performed by a reputable laboratory should be even more accurate.