Given below is a list of few sexually transmitted infections .Which of the diseases is caused by bacteria among these?
(i) Gonorrhoea
(ii) Amoebiasis
(iii) Trichomoniasis
(iv) Chancroid
(v) Syphilis

i,iv and v

Infections or diseases which are transmitted through sexual intercourse are collectively called sexually transmitted infections (STI) or venereal diseases (VD) or reproductive tract infections (RTI). Gonorrhoea, syphilis, genital herpes, chlamydiasis, genital warts, trichomoniasis, hepatitis-B and of course, the most discussed infection in the recent years, HIV leading to AIDS are some of the common STIs. 

Some of these infections like hepatitis–B and HIV can also be transmitted by sharing of injection needles, surgical instruments, etc., with infected persons, transfusion of blood, or from an infected mother to the foetus too. Except for hepatitis-B, genital herpes and HIV infections, other diseases are completely curable if detected early and treated properly.

Syphilis,Chancroid and Gonorrhoea are bacterial STDs. Trichomoniasis and Amoebiasis are caused by protozoans.