'Don't go out while it rains' In this sentence 'while is a/an-

Give her a telephone number to ring ……… she gets lost. Tell me _ that. Water boils _ you heat it to 100° centigrade. ........ you start now, you will be late. 'He could not win but learnt a lot.' Which part of speech is the word 'but'? 'He is poor but honest.' _ in this sentence which is conjunction? I will write down the phone number ____ I forget It is health _ is wealth. The children studied in a class room _ windows were never opened. 'I shall help you provided you obey me.' Here the underlined word is a/an-