i will put 1 and half bitcoin to exchange that and then i will save that. and the other bitcoin i will use for trading
If you like to save your bitcoin in more secure place than exchange platform is not a safer place for sure as exchange platform can't be considered secure enough for long term. Bitcoins that you will not be using for trading should be stored in paper wallets or bitcoin hardware wallets etc.
Yeah keeping them on exchange can be risky as it may disappear or close down in future which will result in loss, if you are only going to save them then its better to save them in secure wallets.