Exercise 11.9
What protective devices can be used during sexual activity to reduce the spread of STIs?
Not cross-checked
NCERT prints no numerical answer for this exercise, so this working has not been cross-checked against the book.
Condoms are the protective device used to reduce the spread of STIs.
They act as a barrier, so the infection is not passed from an infected person to an uninfected one during close physical contact.
The same barrier also stops sperm from reaching the egg, so a condom prevents pregnancy as well.
This matters because the STIs named in the chapter — gonorrhoea, herpes, syphilis, genital warts and HIV (which can eventually lead to AIDS) — include some that are not curable yet, so prevention is the only reliable protection.