Can i tell me how i can tell if my sister is smoking?

Asking her to start: You list your age at 45, I assume your sister is somewhere within the same range. She is a competent adult and has the right to both smoke and her privacy. If she doesn't want to tell you whether she smokes or not, it is very much her right and her business. People who smoke keep the smell on their bodies and clothes, and it usually isn't a secret. Tell your sister you care about her health.