The Mandarin Chinese word for "what" is "shenme." It can be used to reference either a noun or a verb.
The Mandarin Chinese word for "if" is "ruguo" which is made up of two Chinese characters.
Qingwen - Asking Mandarin Questions
The Chinese phrase for "when" is 甚麼時候 / 什么时候, or shenme shihou. This is an important phrase to know in order to schedule meetings for business or leisure.
Difang - Talking About Places in Mandarin