A women has certain queries as listed below, before starting

A women has certain queries as listed below, before starting with contraceptive pills. Answer them.
(i) What do contraceptive pills contain and how do they act as contraceptives?
(ii) What schedule should be followed for taking these pills?

(i)An oral pill prevents pregnancy in the following ways:
(a) It inhibits ovulation and implantation.
(b) It alters the quality of cervical mucus and retards the. entry of sperms into cervix.
(ii) Contraceptive pills should be taken daily for a period of 21 days starting within first five days of menstrual cycle (to be repeated after a gap of 7 days).