is it possible to watch the events of any ethereum transaction? like for erc20 token. when we make any transaction of erc20 on the blockchain event get trigger. is same is possible for ETH transaction. if yes then how we get the ethereum log??
Yes, that is possible. Watch for new blocks and process all transactions.
For each transaction you can run eth_getTransactionReceipt And the logs array will contain all the events
logs: Array - Array of log objects, which this transaction generated.