Periods was due on august 4th .. was delayed .. so had unprotected sex on 7th august.. can this intercourse lead to pregnancy?

Yes: Yes, you can get pregnant, if you sill have not had a period. then ovulation may have been delayed as well.

Late period: With a late period at age 22, it is possible to be pregnant. If your period did occur, having sex on August 7th , assuming this was "during" your period, can still on some occasions cause pregnancy. Wait another week or so and get a serum HCG test to be certain you are not pregnant.