I would like to know if i use Instant Exchange
https://exch.cx/ and convert my bitcoins to litecoin, will it serve as a mixing too and my coins can't be traced (act as a mixer) ?
I will advice you to use monero.
Meaning if i do multiple transactions using that Instant Exchange and convert Bitcoin to Litecoin. (The destination address of LTC remains the same in all the transactions )
That should not be a prove that it acts as a mixer. If you are not exchanging to a privacy coin like monero, the transaction can be traced by the government and
https://exch.cx/Monero is the primary con that you can use. I will recommend you to exchange it on a decentralized exchange like bisq.